[joezydeco]

That's a pretty cool idea.

I'm still wary about the whole concept of letting the customer access the POS interface. What's to keep the customer from subtracting a few items off the tab while the barista is away and working?

Flipping the case over and letting the UI switch into a "signature capture only" mode might be a nice way to solve that.

[tghw]

That's exactly how it works. The barista puts in the items and then it goes into signature mode where you choose a tip and sign.

[astrodust]

Bolting a second iPad into the system, like a Mini, might solve this problem, where it's locked into the signature mode unless doing something like advertising.