Cash return display when split payment

When making split payment it would be useful to be able to see how much cash to give back to customer when total amount is over required sum. We accept different kind of sport checks and customer might pay 9 € purchase with 2x4 € checks and 5 € cash. It's not hard to calculate this but when things get busy it helps a lot not to have to think too much.

This of course only applies if cash is used as payment with split method.

thanks,
kalle