UbarTab

It's great! Not too deep. Simple interface and well thought out. Even my Jpn staff can use it. No documentation though so not sure about a few things about Tab Update".

We're a fabric store and we use the app to cut fabric at one register and save the customer's cart. They can keep shopping and then checkout at another register.
I just wish that the app would automatically release inventory when loading a cart (Instead of offering you the choice to keep the hold). This might not matter for some use cases and probably doesn't for restaurants, but for a retail store we think having the option is strange. It isn't a big deal, we just don't use the option.
Great app and the only one that way to easily start an invoice on one device and finish it on another.