diff --git a/addons/point_of_sale/static/src/js/models.js b/addons/point_of_sale/static/src/js/models.js
index 009ad0e992b..29d882f5878 100644
--- a/addons/point_of_sale/static/src/js/models.js
+++ b/addons/point_of_sale/static/src/js/models.js
@@ -2560,10 +2560,16 @@ exports.Order = Backbone.Model.extend({
                 if (lines[i].get_product() === tip_product) {
                     lines[i].set_unit_price(tip);
                     lines[i].set_lst_price(tip);
+                    lines[i].price_manually_set = true;
                     return;
                 }
             }
-            this.add_product(tip_product, {quantity: 1, price: tip, lst_price: tip });
+            this.add_product(tip_product, {
+              quantity: 1,
+              price: tip,
+              lst_price: tip,
+              extras: {price_manually_set: true},
+            });
         }
     },
     set_pricelist: function (pricelist) {