POS Offline add Notes (Currency) buttons

Hi all,
Maybe is nothing but useful as in other POS you find those buttons with small and higher bill notes according or depending on the country… for instance in mine note bills mostly used to pay are 500, 1000, 2000 and 5000.

So for the Cashier to register a Cash payment of 1200 he/she has to C (clear) first and then click the number on screen (Touch) or type on the keyboard the value if given by the customer 2000

So customized (configured on POS what Note Bills to add) buttons should be added like the screen below and the action on those buttons should be like Current value on payment_val = flt(payment_val) + flt($(this).text()) which means that after the user click on CASH or Clear and click once on the Bills it will just Sum instead of adding.