These would be great for decorating our new tower shops. I can see this happening one of two ways, depending on how much scripting work gets done. Naturally, I'd much rather see the scripted version, but I can understand if there isn't enough support in the code for something like it at the present time.
Simple Version: A simple Tabletop Decoration version of a cash register, or ideally a selection of a few of them, including everything from a modernish register to one of those old-fashioned mechanical models with the little monetary value cards that pop up when the buttons are pushed down.
Scripted Version: This would be it's own craftable item, perhaps with customisable looks as above. And, as a convenience factor, the owner of a building could click on the register to get two options to make it easier to collect profits from all our sales boxes: One option collects the currants from all boxes on the same floor as the register, and the other option collects it from the entire building.