I have my sister who's a CA (we still pay her for her time). I buy DC food with family food. We just highlight what we bought for the daycare on the receipt, then put what we bought (with the price, date, and location) in a spreadsheet. All the receipts go into an envelope (with different months). Same goes with toys, and any equipment I may buy for the DCKs!

This is something that my sister has suggested us to do and it works for us.