Rental, Payment Rental.

Cart filled with rubbish Sometimes the customer has to pay a small deposit by inserting a coin, which is returned if and when the customer returns the cart to a designated cart parking point. Some retailers sell "trolley tokens" as an alternative to coins, often for charity. The mechanism can often be unlocked by inserting a key into the slot to open the lock.

This is also done for profit with luggage carts at many airports, where companies like Smarte Carte charge two or more dollars (U.S.) (or equivalent) for rental, and return a small token reward of a quarter (25 ¢) for returning carts to the other end of any dispenser machine.