Cash register
A cash register or till (British English
British English
British English, or English , is the broad term used to distinguish the forms of the English language used in the United Kingdom from forms used elsewhere...

) is a mechanical or electronic device for calculating and recording sales transactions, and an attached cash drawer
Cash drawer
A cash drawer is generally a compartment underneath a cash register in which the cash from transactions is kept. The drawer typically contains a removable till. The till is usually divided into compartments used to store each denomination of bank notes and coins separately to make counting easier...

 for storing cash
In common language cash refers to money in the physical form of currency, such as banknotes and coins.In bookkeeping and finance, cash refers to current assets comprising currency or currency equivalents that can be accessed immediately or near-immediately...

. The cash register also usually prints a receipt
A receipt is a written acknowledgment that a specified article or sum of money has been received as an exchange for goods or services. The receipt is evidence of purchase of the property or service obtained in the exchange.-Printed:...

 for the customer.

In most cases the drawer can be opened only after a sale, except when using special keys
Key (lock)
A key is an instrument that is used to operate a lock. A typical key consists of two parts: the blade, which slides into the keyway of the lock and distinguishes between different keys, and the bow, which is left protruding so that torque can be applied by the user. The blade is usually intended to...

, which only senior employees and the owner have. This reduces the risk of employees stealing from the shop owner by not recording a sale and pocketing the money, when a customer does not need a receipt but has to be given change (cash is more easily checked against recorded sales than inventory
Inventory means a list compiled for some formal purpose, such as the details of an estate going to probate, or the contents of a house let furnished. This remains the prime meaning in British English...