Fix for rare edge case where POS saving partially unpaid sale document to BO. Example: A sale has several payment tenders (CARD 20, CARD 10). During processing, the first payment (CARD 20 ) is paid but the second payment fails (CARD 10). The POS user tries to process the failed payment in a second attempt. If the payment is Partial (the approved charged amount is less than the requested amount - less than 10), POS updates the payment amount, BUT instead of keeping the POS user in Payment Screen, it automatically saves the sale document to BO as Unpaid.