The cashier reviews the invoice and inputs the sale. The cash register mechanically validates the invoice by automatically assigning a consecutive number to the transaction. The cashier is also responsible for getting credit approval on charge sales and approving sales paid by check. The cashier gives one copy of the invoice to the customer and retains the second copy as a store copy and the third for a bank card, if a deposit is needed. Returns are handled in exactly the reverse manner, with the cashier issuing a return slip.