Split This Bill app for iPhone and iPad

Split This Bill is the easiest way to evenly split a bill between a number of people. It automatically calculates the tip based on a percentage of the untaxed amount. Single-tap Round Up and Round Down buttons make it easy to make change, recalculating the tip and tip percentage to make any of the fields an even amount. Editing any field automatically recalculates the others. You can choose to start from default values for the number of people, tax rate, and tip rate in order to speed data entry.

If you are looking for an easier tip calculator and bill splitter, you wont find one.