The cash register this place uses is also two layers of #RetroComputing interest:

The physical computer is what I believe is a Mac Mini G4 running OS X (which would mean 10.3-10.5).

The register software it runs is much, much older, however. I can't be sure of the software's resolution, but it *looked* like the 512x342 of the original compact Macs, and it was definitely rendered in 1-bit B&W.

I commented on the setup, and the guy just kind of shrugged and said it was an antique shop.

Fair.