diff --git a/app/controllers/api/cart_controller.rb b/app/controllers/api/cart_controller.rb
index c9de2170d..82cc48615 100644
--- a/app/controllers/api/cart_controller.rb
+++ b/app/controllers/api/cart_controller.rb
@@ -31,6 +31,12 @@ class API::CartController < API::ApiController
     render 'api/orders/show'
   end
 
+  def set_offer
+    authorize @current_order, policy_class: CartPolicy
+    @order = Cart::SetOfferService.new.call(@current_order, orderable, cart_params[:is_offered])
+    render 'api/orders/show'
+  end
+
   private
 
   def orderable
diff --git a/app/controllers/concerns/api/order_concern.rb b/app/controllers/concerns/api/order_concern.rb
index 9e14854dd..6c0b753c1 100644
--- a/app/controllers/concerns/api/order_concern.rb
+++ b/app/controllers/concerns/api/order_concern.rb
@@ -17,6 +17,6 @@ module API::OrderConcern
   end
 
   def cart_params
-    params.permit(:order_token, :orderable_id, :quantity, :user_id)
+    params.permit(:order_token, :orderable_id, :quantity, :user_id, :is_offered)
   end
 end
diff --git a/app/frontend/src/javascript/api/cart.ts b/app/frontend/src/javascript/api/cart.ts
index 4601de322..f0efea8db 100644
--- a/app/frontend/src/javascript/api/cart.ts
+++ b/app/frontend/src/javascript/api/cart.ts
@@ -22,4 +22,9 @@ export default class CartAPI {
     const res: AxiosResponse<Order> = await apiClient.put('/api/cart/set_quantity', { order_token: order.token, orderable_id: orderableId, quantity });
     return res?.data;
   }
+
+  static async setOffer (order: Order, orderableId: number, isOffered: boolean): Promise<Order> {
+    const res: AxiosResponse<Order> = await apiClient.put('/api/cart/set_offer', { order_token: order.token, orderable_id: orderableId, is_offered: isOffered });
+    return res?.data;
+  }
 }
diff --git a/app/frontend/src/javascript/components/cart/store-cart.tsx b/app/frontend/src/javascript/components/cart/store-cart.tsx
index 8e06369fd..f385d3821 100644
--- a/app/frontend/src/javascript/components/cart/store-cart.tsx
+++ b/app/frontend/src/javascript/components/cart/store-cart.tsx
@@ -115,8 +115,12 @@ const StoreCart: React.FC<StoreCartProps> = ({ onSuccess, onError, currentUser,
   /**
    * Toggle product offer
    */
-  const onSwitch = (product, checked: boolean) => {
-    console.log('Offer ', product.orderable_name, ': ', checked);
+  const toogleProductOffer = (item) => {
+    return (checked: boolean) => {
+      CartAPI.setOffer(cart, item.orderable_id, checked).then(data => {
+        setCart(data);
+      }).catch(onError);
+    };
   };
 
   /**
@@ -128,14 +132,50 @@ const StoreCart: React.FC<StoreCartProps> = ({ onSuccess, onError, currentUser,
     }
   };
 
+  /**
+   * Get the item total
+   */
+  const itemAmount = (item): number => {
+    return item.quantity * Math.trunc(item.amount * 100) / 100;
+  };
+
+  /**
+   * return true if cart has offered item
+   */
+  const hasOfferedItem = (): boolean => {
+    return cart.order_items_attributes
+      .filter(i => i.is_offered).length > 0;
+  };
+
   /**
    * Get the offered item total
    */
   const offeredAmount = (): number => {
     return cart.order_items_attributes
       .filter(i => i.is_offered)
-      .map(i => i.amount)
-      .reduce((acc, curr) => acc + curr, 0);
+      .map(i => Math.trunc(i.amount * 100) * i.quantity)
+      .reduce((acc, curr) => acc + curr, 0) / 100;
+  };
+
+  /**
+   * Get the total amount before offered amount
+   */
+  const totalBeforeOfferedAmount = (): number => {
+    return (Math.trunc(cart.total * 100) + Math.trunc(offeredAmount() * 100)) / 100;
+  };
+
+  /**
+   * Get the coupon amount
+   */
+  const couponAmount = (): number => {
+    return (Math.trunc(cart.total * 100) - Math.trunc(computePriceWithCoupon(cart.total, cart.coupon) * 100)) / 100.00;
+  };
+
+  /**
+   * Get the paid total amount
+   */
+  const paidTotal = (): number => {
+    return computePriceWithCoupon(cart.total, cart.coupon);
   };
 
   return (
@@ -163,7 +203,7 @@ const StoreCart: React.FC<StoreCartProps> = ({ onSuccess, onError, currentUser,
               </select>
               <div className='total'>
                 <span>{t('app.public.store_cart.total')}</span>
-                <p>{FormatLib.price(item.quantity * item.amount)}</p>
+                <p>{FormatLib.price(itemAmount(item))}</p>
               </div>
               <FabButton className="main-action-btn" onClick={removeProductFromCart(item)}>
                 <i className="fa fa-trash" />
@@ -175,7 +215,7 @@ const StoreCart: React.FC<StoreCartProps> = ({ onSuccess, onError, currentUser,
                   <span>Offer the product</span>
                   <Switch
                   checked={item.is_offered}
-                  onChange={(checked) => onSwitch(item, checked)}
+                  onChange={toogleProductOffer(item)}
                   width={40}
                   height={19}
                   uncheckedIcon={false}
@@ -203,7 +243,7 @@ const StoreCart: React.FC<StoreCartProps> = ({ onSuccess, onError, currentUser,
 
       <aside>
         {cart && !cartIsEmpty() && isPrivileged() &&
-          <div> <MemberSelect onSelected={handleChangeMember} /></div>
+          <div> <MemberSelect onSelected={handleChangeMember} defaultUser={cart.user as User} /></div>
         }
 
         {cart && !cartIsEmpty() && <>
@@ -211,17 +251,17 @@ const StoreCart: React.FC<StoreCartProps> = ({ onSuccess, onError, currentUser,
             <h3>{t('app.public.store_cart.checkout_header')}</h3>
             <span>{t('app.public.store_cart.checkout_products_COUNT', { COUNT: cart?.order_items_attributes.length })}</span>
             <div className="list">
-              <p>{t('app.public.store_cart.checkout_products_total')} <span>{FormatLib.price(cart.total)}</span></p>
-              {offeredAmount() > 0 &&
+              <p>{t('app.public.store_cart.checkout_products_total')} <span>{FormatLib.price(totalBeforeOfferedAmount())}</span></p>
+              {hasOfferedItem() &&
                 <p className='gift'>{t('app.public.store_cart.checkout_gift_total')} <span>-{FormatLib.price(offeredAmount())}</span></p>
               }
-              {cart.coupon && computePriceWithCoupon(cart.total, cart.coupon) !== cart.total &&
-                <p>{t('app.public.store_cart.checkout_coupon')} <span>{FormatLib.price(-(cart.total - computePriceWithCoupon(cart.total, cart.coupon)))}</span></p>
+              {cart.coupon &&
+                <p>{t('app.public.store_cart.checkout_coupon')} <span>-{FormatLib.price(couponAmount())}</span></p>
               }
             </div>
-            <p className='total'>{t('app.public.store_cart.checkout_total')} <span>{FormatLib.price(computePriceWithCoupon(cart.total, cart.coupon))}</span></p>
+            <p className='total'>{t('app.public.store_cart.checkout_total')} <span>{FormatLib.price(paidTotal())}</span></p>
           </div>
-          <FabButton className='checkout-btn' onClick={checkout}>
+          <FabButton className='checkout-btn' onClick={checkout} disabled={!cart.user}>
             {t('app.public.store_cart.checkout')}
           </FabButton>
         </>}
diff --git a/app/frontend/src/javascript/components/coupon/coupon-input.tsx b/app/frontend/src/javascript/components/coupon/coupon-input.tsx
index 56cccba6c..f1cbb8823 100644
--- a/app/frontend/src/javascript/components/coupon/coupon-input.tsx
+++ b/app/frontend/src/javascript/components/coupon/coupon-input.tsx
@@ -27,13 +27,20 @@ export const CouponInput: React.FC<CouponInputProps> = ({ user, amount, onChange
   const [loading, setLoading] = useState<boolean>(false);
   const [error, setError] = useState<boolean>(false);
   const [coupon, setCoupon] = useState<Coupon>();
+  const [code, setCode] = useState<string>();
 
   useEffect(() => {
-    if (user && coupon) {
-      handleChange(coupon.code);
+    if (user && code) {
+      handleChange(code);
     }
   }, [user]);
 
+  useEffect(() => {
+    if (code) {
+      handleChange(code);
+    }
+  }, [amount]);
+
   /**
    * callback for validate the code
    */
@@ -42,6 +49,7 @@ export const CouponInput: React.FC<CouponInputProps> = ({ user, amount, onChange
     setMessages([]);
     setError(false);
     setCoupon(null);
+    setCode(value);
     if (value) {
       setLoading(true);
       CouponAPI.validate(value, amount, user?.id).then((res) => {
diff --git a/app/frontend/src/javascript/components/user/member-select.tsx b/app/frontend/src/javascript/components/user/member-select.tsx
index 98c7a114c..dfcadf35e 100644
--- a/app/frontend/src/javascript/components/user/member-select.tsx
+++ b/app/frontend/src/javascript/components/user/member-select.tsx
@@ -29,6 +29,12 @@ export const MemberSelect: React.FC<MemberSelectProps> = ({ defaultUser, onSelec
     }
   }, []);
 
+  useEffect(() => {
+    if (!defaultUser && value) {
+      onSelected(value.value);
+    }
+  }, [defaultUser]);
+
   /**
    * search members by name
    */
diff --git a/app/frontend/src/javascript/lib/coupon.ts b/app/frontend/src/javascript/lib/coupon.ts
index 7dd8da184..c0eef00e2 100644
--- a/app/frontend/src/javascript/lib/coupon.ts
+++ b/app/frontend/src/javascript/lib/coupon.ts
@@ -5,9 +5,9 @@ export const computePriceWithCoupon = (price: number, coupon?: Coupon): number =
     return price;
   }
   if (coupon.type === 'percent_off') {
-    return price - (price * coupon.percent_off / 100.00);
+    return (Math.trunc(price * 100) - (Math.trunc(price * 100) * coupon.percent_off / 100)) / 100;
   } else if (coupon.type === 'amount_off' && price > coupon.amount_off) {
-    return price - coupon.amount_off;
+    return (Math.trunc(price * 100) - Math.trunc(coupon.amount_off * 100)) / 100;
   }
   return price;
 };
diff --git a/app/policies/cart_policy.rb b/app/policies/cart_policy.rb
index 4bacdda1e..4772323f4 100644
--- a/app/policies/cart_policy.rb
+++ b/app/policies/cart_policy.rb
@@ -13,4 +13,8 @@ class CartPolicy < ApplicationPolicy
       record.statistic_profile_id.nil? && record.operator_profile_id.nil?
     end
   end
+
+  def set_offer?
+    user.privileged?
+  end
 end
diff --git a/app/services/cart/add_item_service.rb b/app/services/cart/add_item_service.rb
index 298aafbc8..aae1fd32f 100644
--- a/app/services/cart/add_item_service.rb
+++ b/app/services/cart/add_item_service.rb
@@ -15,7 +15,7 @@ class Cart::AddItemService
     else
       item.quantity += quantity.to_i
     end
-    order.total += (orderable.amount * quantity.to_i)
+    order.total += (item.amount * quantity.to_i)
     ActiveRecord::Base.transaction do
       item.save
       order.save
diff --git a/app/services/cart/remove_item_service.rb b/app/services/cart/remove_item_service.rb
index cfa43c1ef..09890a973 100644
--- a/app/services/cart/remove_item_service.rb
+++ b/app/services/cart/remove_item_service.rb
@@ -7,7 +7,7 @@ class Cart::RemoveItemService
 
     raise ActiveRecord::RecordNotFound if item.nil?
 
-    order.total -= (item.amount * item.quantity.to_i)
+    order.total -= (item.amount * item.quantity.to_i) unless item.is_offered
     ActiveRecord::Base.transaction do
       item.destroy!
       order.save
diff --git a/app/services/cart/set_offer_service.rb b/app/services/cart/set_offer_service.rb
new file mode 100644
index 000000000..a5d2ac38f
--- /dev/null
+++ b/app/services/cart/set_offer_service.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+# Provides methods for set offer to item in cart
+class Cart::SetOfferService
+  def call(order, orderable, is_offered)
+    item = order.order_items.find_by(orderable: orderable)
+
+    raise ActiveRecord::RecordNotFound if item.nil?
+
+    if !item.is_offered && is_offered
+      order.total -= (item.amount * item.quantity)
+    elsif item.is_offered && !is_offered
+      order.total += (item.amount * item.quantity)
+    end
+    item.is_offered = is_offered
+    ActiveRecord::Base.transaction do
+      item.save
+      order.save
+    end
+    order.reload
+  end
+end
diff --git a/app/services/cart/set_quantity_service.rb b/app/services/cart/set_quantity_service.rb
index 396716de5..400c622c1 100644
--- a/app/services/cart/set_quantity_service.rb
+++ b/app/services/cart/set_quantity_service.rb
@@ -12,7 +12,7 @@ class Cart::SetQuantityService
     raise ActiveRecord::RecordNotFound if item.nil?
 
     different_quantity = quantity.to_i - item.quantity
-    order.total += (orderable.amount * different_quantity)
+    order.total += (item.amount * different_quantity) unless item.is_offered
     ActiveRecord::Base.transaction do
       item.update(quantity: quantity.to_i)
       order.save
diff --git a/config/routes.rb b/config/routes.rb
index 59fe26096..428c5f8e8 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -159,6 +159,7 @@ Rails.application.routes.draw do
       put 'add_item', on: :collection
       put 'remove_item', on: :collection
       put 'set_quantity', on: :collection
+      put 'set_offer', on: :collection
     end
     resources :checkout, only: %i[] do
       post 'payment', on: :collection