Looks like there are tons of tip calculators on the android market. Nevertheless since we already did it as part of Advanced Financial Calculator, we extracted it out and made it a free app so that it is available to everyone. What we like about it is that in addition to the tip splitting and rounding features that other tip apps have, it also can save the tips into history and bring it back any time. All previous inputs are remembered so next time to find out the tip, all you need to do is to input the bill total, simple as that. You can even email it to your own email address to keep a record or to your friend to remind he/she owes you some money since you pay the bill this time. It kind of changes from a simple tipping app to a prefect application to keep track of all the dinning expenses. You may want keep an eye on it as you might know already, dinning expense could be huge sometimes.
Here are some screenshots.