Page "Cash register" Paragraph 2

In most cases the drawer can be opened only after a sale, except when using special keys, which generally only the owner ( if not also some employees ) have.

This reduces the risk of employees stealing from the shop owner by pocketing the money without recording a sale, when a customer does not need a receipt but has to be given change ( cash is more easily checked against recorded sales than inventory ).

In fact, cash registers were invented for the purpose of eliminating employee theft or embezzlement ; the original name was Incorruptible Cashier.

It has also been suggested that odd pricing came about because by charging odd amounts like 49 or 99 cents, the cashier very probably had to open the till for the penny change and thus announce the sale.