Abstract: A device for monitoring the coins in one or more coin tubes on a vending machine to maintain a running total of the coins therein that are available to pay back excess deposits and to make refunds. The device may include one or more coin tubes for containing a supply of coins of respective denominations, the coin tubes being included in a coin unit for receiving coins deposited in the vending machine and for directing the coins to the respective coin tubes. The coin unit includes an accumulator associated with each coin tube for counting each coin that enters therein and for subtracting therefrom the number of coins paid out, each of the accumulators including a mechanism for establishing a minimum and a maximum number of coins that can be maintained in the coin tube.