Cash drawer/receipt printing with iPad?

[LaSombraEVV]

Does anybody know how to connect a cash drawer/printer terminal for receipts to an iPad without paying for ShopKeep (and others)? It looks like it should be possible to do it via USB, but I can't seem to find any information on how to go about this without having to pay for it. Like a Square type app that can pop a cash drawer and print a receipt?

Thank you!

- La Sombra