1. Prohibit illegal Input .
2. Prohibit mean-less input.
3. Big input button, easy to use.
4. Undo function.
5. Display until and only until cents.
6. Default tip percentage: 10%.
Design for: iPhone 6, iPhone 6 plus, iPhone 5, iPhone 5s, iphone 4s, resizable iPhone, ipad 2, ipad Air, ipad Retina, Resizable ipad.
Suport: [email protected].