I use excel to keep track of payments.. A spreadsheet with the childs name, date money was recieved and amount.
I will give annual reciept in Dec/January.. for each child with total amount paid to me.
It sounds like I can keep doing what I am doing.. I thought of banking it but then we just end up using the debit card to pay for groceries, gas etc. It seems silly to drive to the bank just to deposit just to withdraw it at the grocery store a hour later.

Thanks for all the info.