Working with money

Hi Again, its been a while now.

I am worknig on a new project and i was wondering if anyone could give me some advice.

This is a device supposed to work any place in the world, and hence my complications.

Can someone give advice on how to work with the money??
How to store it? How many Bytes would you store?

How can you work out the cents, hoy many words would you use to store for example dollars, how would you store dollars (i am guessing 3 bytes is enough) and later how would you retrieve them, how do you print on an LCD a 3 bytes number?

The fact is that there seems to be a lot of math operations and someone must have done this before...*/, ** , div32, etc.

To give you an idea suppose that this is a Cash machine, also there will be maths applied between this X sized values. For example adding them.

Thanks for any advice