Square is AMAZING!!! You do have to have a smart phone and wifi or data to use it. We use it at our storefront and will be using it at fairs once we get some scheduled.
You will link your bank account to it and they only charge a small percentage out of the total. Nicest thing is that you can add or remove tax with just the touch of a button.
We got an iPad for it where you can have the Square Register APP and you can put in your inventory. That way you know exactly what you sold.