Hi,
You may be able to use it with a micro; it looks like there are about 20 connections, so I am guessing it would be parallel interface. I would try googling for dot matrix printers, and see what you come up with for interfaces. You will also have to do some expeerimenting to figure out the connections. It should be easy to figure out which wires are power and ground. It looks like there is a number printed on the thing, but I can't see the photo now, as I'm replying. Can you do a search on that number? Also, which cash register did it come from? You may find a data sheet, or at least a wiring diagram for the cash register.
I think this would make a good project!
Best wishes,
Robert