[FIX] point_of_sale: round subtotal of orderline according to currency
[FIX] point_of_sale: round subtotal of orderline according to currency

Before this we used line.price_subtotal directly when creating
account.move.line records, which causes issues when dealing with
non-integer quantities. In that case the amount paid by a POS customer
will never accurately be able to match the total computed amount of the
order.

opw-672118

storm-computers/odoo,storm-computers/odoo,Elico-Corp/odoo_OCB,stephen144/odoo,ygol/odoo,Elico-Corp/odoo_OCB,sysadminmatmoz/OCB,ygol/odoo,sysadminmatmoz/OCB,bplancher/odoo,microcom/odoo,Elico-Corp/odoo_OCB,storm-computers/odoo,hip-odoo/odoo,storm-computers/odoo,storm-computers/odoo,bplancher/odoo,dfang/odoo,dfang/odoo,hip-odoo/odoo,stephen144/odoo,ygol/odoo,Elico-Corp/odoo_OCB,laslabs/odoo,sysadminmatmoz/OCB,laslabs/odoo,sysadminmatmoz/OCB,stephen144/odoo,sysadminmatmoz/OCB,stephen144/odoo,laslabs/odoo,bplancher/odoo,hip-odoo/odoo,microcom/odoo,bplancher/odoo,microcom/odoo,storm-computers/odoo,microcom/odoo,microcom/odoo,ygol/odoo,ygol/odoo,dfang/odoo,Elico-Corp/odoo_OCB,microcom/odoo,ygol/odoo,dfang/odoo,sysadminmatmoz/OCB,hip-odoo/odoo,stephen144/odoo,hip-odoo/odoo,ygol/odoo,Elico-Corp/odoo_OCB,laslabs/odoo,bplancher/odoo,sysadminmatmoz/OCB,laslabs/odoo,stephen144/odoo,bplancher/odoo,laslabs/odoo,hip-odoo/odoo,dfang/odoo,dfang/odoo