That's cheating.

Let's break up in denomination of less than $1, 25¢, 10¢ and 5¢, respectively.

So to make anything less than $1, you'll need 3 quarters max.
Less than 25¢: 2 dimes max.
Less than 10¢: 1 nickel max.
Less than 5¢: 4 pennies max.

So 3 quarters, 2 dimes, 1 nickel and 4 pennies will make anything 1-99¢. The amount of coins when you enter will be at minimum and when you go out will also be at minimum since the cashier won't give you any change.

Or else you can carry one $1 coin (we have that in Canada, dunno in US) and the cashier will give minimum change.

i say this is the same as my original answer event though i didnt explain all of it or understand the problem

depends is it just when you leave that you count coin or the average of when you left/entered?

isnt it 4 pennies one nickel two dimes and 3 quarters since you can make any change out of that combination

for 1-4 cents use the pennies
for 5-9 use one nickel and the neccesary pennies
for 10-19 use 1  dime and the pennies/nickel for the remainder
for 20-24 use two dimes and pennies
for 25-29 use quarter and pennies
for 30-34 use quarter, nickel and pennies
for 35-39 use quarter, dime and pennies
etc.

and i have 3 half dollars if you look for them they are still rare but not too hard to find a few
I also have a dollar coin and thats pretty rare or at least used to be

I'm slowly working through the errors but I am finding things that are missing that need to be added to the SDK for it to compile.
The things I've found so far that need implementation are:
stdint.h (Though i think I got this working acceptably you can see my slightly modified version of it in the include folder of the most recent commit)
stdarg.h(for va_list)
and probably more but until I get past one I can't see the next problems

2915: You panic when you realize your friend who goes to another school has your calc and feel insanely relieved when you get it back 2 weeks later(not that this is any specific story)

Thanks for now I'll just run through the tests and see how that works once I get my calc

I have been working on porting nSDL to the prizm so people can write one program to run on both prizm and both nspires. It now even compiles for on calc so it should be ready for anyone who wants to to test it. Until it gets to version 1 and I get most bugs out I will not be distributing binaries so you will have to build it. To compile it run make -f Makefile.prizm and it should compile. to install it assumes you built it in the /projects directory of the prizm sdk then run make -f Makefile.prizm install to install it to your prizm sdk

I need people to help me find any errors I might have made and to test the library. If someone could please help me the code is at https://github.com/ruler501/pSDL It now compiles fine and will run if you use a 8 bit surface. malloc seems to fail if it tries to use a 16bpp surface the size of the screen. If someone could please find a way to get malloc working with large values that could allow much more usability

I could not have done this without hoffa's wonderful nSDL. I have copied most of his code and only changed the parts that are platform specific(mainly).

DEMO:

This is a demo of a program called explosion I cannot currently remember where I got it from. Other than removing functions the prizm doesnt support very little work was needed to port it

Attatched is the binaries for version 1.0.0 I will be updating soon since the current version does not support anywhere near the whole keyboard like it should.
pSDL has also moved so that it is now called pSDL on my github instead of still being called nSDL

EDIT:Touched up the entire post to be more concise and orderly