A cash drawer plugs into your receipt printer. The drawer will pop open after a sale is completed and the receipt starts printing. We recommend these devices from Star Micronics:
Windows, Mac, and iPad
Star SMD2-1317
Star SMD2-1617
Star CD3-1313
Star CD3-1616
Star CD4-1416
Star CD4-1616
Star mPOS for iPad (Bluetooth)