[FIX] point_of_sale: cash rounding on invoice

When an invoice is created from pos having a cash rounding method, the
value of the rounding can depend on the payment methods.

When no rounding has been applied because of the order has been
partially paid by cash and bank, the rounding line should be deleted
from the invoice. We should also adapt the terms lines.

closes odoo/odoo#71375

Signed-off-by: pimodoo <pimodoo@users.noreply.github.com>