Abstract: In one aspect, the present invention is directed to a cash register machine, comprising: an expected currency calculator; and an actual currency calculator, employing one or more sensors for the operation thereof. The sensor(s) may detect whether a banknote is placed into a compartment of the machine, whether a banknote is removed from a compartment of the machine, and so on. According to one embodiment of the invention, the sensors comprise: a first sensor for detecting an operation of placing or removing an object from a compartment of the machine, and a second sensor for determining whether the operation is placing or removing. The machine may further comprise image processing means. The image processing means may be employed for decoding the content of a check, credit card voucher, banknote, and so on.