[FIX] point_of_sale: correctly round total due in payment screen

Current behavior:
When you make a purchase that should be rounded down, for example 1.97
rounded down to 1.95. On the payment screen if you select a payment
method and pay with a greater amount than the base amount. The total due
would be rounded incorrectly to 2.00 instead of 1.95.

Steps to reproduce:
- Create a product with a price of 1.97
- Set a rouding down method of 0.05
- Open a pos session
- Add the product to the order
- Select a payment method, for example cash and enter an amount greater
  than the base amount, for example 5.00
- The total due will be 2.00 instead of 1.95

opw-3175726

closes odoo/odoo#114427

X-original-commit: 45994a5f8b3f87c46e39c260183663023d51e080
Signed-off-by: Heinz Robin (rhe) <rhe@odoo.com>
Signed-off-by: Engels Robin (roen) <roen@odoo.com>

addons/point_of_sale/static/src/js/models.js

@@ -3711,7 +3711,7 @@ export class Order extends PosModel {
                     (this.get_total_with_tax() < 0 && remaining > 0) ||
                     (this.get_total_with_tax() > 0 && remaining < 0)
                 ) {
-                    rounding_method = rounding_method.endsWith("UP") ? "DOWN" : rounding_method;
+                    rounding_method = rounding_method.endsWith("UP") ? "DOWN" : "UP";
                 }
 
                 remaining *= sign;

addons/point_of_sale/static/tests/tours/PaymentScreen.tour.js

@@ -172,3 +172,19 @@ PaymentScreen.check.remainingIs('0.0');
 PaymentScreen.check.changeIs('0.0');
 
 registry.category("web_tour.tours").add('PaymentScreenRoundingHalfUp', { test: true, url: '/pos/ui', steps: getSteps() });
+
+startSteps();
+
+ProductScreen.do.clickHomeCategory();
+ProductScreen.exec.addOrderline('Product Test', '1');
+ProductScreen.do.clickPayButton();
+
+PaymentScreen.check.totalIs('1.95');
+PaymentScreen.exec.pay('Cash', '5');
+
+PaymentScreen.check.remainingIs('0.0');
+PaymentScreen.check.changeIs('3.05');
+PaymentScreen.check.totalDueIs('1.95');
+Chrome.do.clickTicketButton();
+
+registry.category("web_tour.tours").add('PaymentScreenTotalDueWithOverPayment', { test: true, url: '/pos/ui', steps: getSteps() });

addons/point_of_sale/static/tests/tours/helpers/PaymentScreenTourMethods.js

@@ -194,6 +194,15 @@ class Check {
             },
         ];
     }
+    totalDueIs(amount) {
+        return [
+            {
+                content: `total due is ${amount}`,
+                trigger: `.payment-status-total-due:contains("${amount}")`,
+                run: () => {},
+            },
+        ];
+    }
 }
 
 class Execute {

addons/point_of_sale/tests/test_frontend.py

@@ -633,6 +633,7 @@ class TestUi(TestPointOfSaleHttpCommon):
 
         self.main_pos_config.open_ui()
         self.start_tour("/pos/ui?config_id=%d" % self.main_pos_config.id, 'PaymentScreenRoundingDown', login="accountman")
+        self.start_tour("/pos/ui?config_id=%d" % self.main_pos_config.id, 'PaymentScreenTotalDueWithOverPayment', login="accountman")
 
     def test_rounding_half_up(self):
         rouding_method = self.env['account.cash.rounding'].create({