[FIX] point_of_sale: rounding in report

- Create a product with price 2335.5, no tax
- Start a POS session
- Add the product, set a discount of 3% on the line => total is 2665.44
- Validate and close the session
- Got to Point of Sale / Reporting / Orders, open the pivot view

The Total Price of the order is 2665.43.

It happens because the server returns a value of 2665.435, which is
displayed in the pivot view as 2665.43.

We round the Total Price based on the company currency decimal
precision. Indeed, all amounts are converted in this currency in the
report.

opw-2369023

closes odoo/odoo#62021

X-original-commit: 178d5c87
Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>