So you would like the option to specify the details of your bill but not be required to do so? Want to quickly determine a tip, enter a subtotal and a tip will be calculated?
Or maybe you want to determine the portion of a bill that you are responsible for? Account for items individually? Something that would allow you to optionally specify the percentage of an individual item that you are responsible for, rather than simply split the total? Account for things you buy more than one of, like drinks? For example if you shared an appetizer with three friends, had an entree and two drinks you might want to be able to enter the full price of the appetizer and your percentage of 25, the price of your entree and then the price of your drink and a quantity of 2. Something like that?
Yes calculators exist that do that. Unfortunately I can not mention the one that I wrote since I am using a vendor/developer account and that would violate forum posting rules. I'm hoping saying this much does not violate the rules.