I am trying to find a finance style calculator app on the app store, but have had no such luck so far...partly because there are so many thousands of calculator apps that it is almost impossible to use the search to find what I'm looking for...

In our office we have several desktop calculators that are have a Tax+ and Tax- button on them.

The way it works is you set your tax rate and then when you enter a value into the calculator you can hit Tax+ and it will apply your tax rate and give you a new total. If you hit the Tax+ button a second time it shows only the tax amount. For example:

Set Tax Rate to 15%

Enter: 100
Press Tax+:
Result: 115
Press Tax+ again:15

The same method works for Tax- except that it treats the value you enter as a Tax inclusive value and it subtracts the tax rate so you can calculate the base price of an item that is listed as including tax.

There are literally dozens of these calculators sold from office supply stores. I have one in the office that is a Canon Tax & Business calculator and another that is made my Panasonic.

However, I simply cannot find an iOS app that does this very standard function.

Anyone seen one like this?