tip calculator - good, cheap app for iPhone and iPad

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. Missing data reminding.
7. Wrong data format reminding.
8. Default tip percentage: 10%.

Design for: iPad Pro, iPad Retina, iPad Air 2, iPad Air, iPad 2, Resizable iPad, (iOS version: 7.1, 8.1, 8.2, 8.3, 8.4).
iPhone 6s, iPhone 6s plus, iPhone 6, iPhone 6 plus, iPhone 5, iPhone 5s, iPhone 4s, resizable iPhone (iOS version: 7.1, 8.1, 8.2, 8.3, 8.4).

Language: English, Chinese-implied, Chinese-traditional.

User Manual:
Undo: Delete one character in the highlighted field.
Clear: Delete all entered data in all fields.
Return: Move the highlighted field to next field to enter data in next field.
Calculate: Calculate the entered data to get result.

To change the default tip percentage value, Click Return to move icon to tip percentage field,
then, click undo to remove the default tip percentage value. After remove the default tip
percentage value, enter a new tip percentage value.

If you find a bug, please send all following info to my email address:
[email protected]. including the following message:

App name.
App version
Device name.
Device version.
Bug description.
Detailed procedure of how to re-produce the bug.