Well, I've done POS systems in the past - my first one was probably 13 years ago, in Clipper - and what I would do is create a hierarchy database of formulas that should be evaluated according to the chain of events in your hierarchy. You can use that not only to discounts, but to other stuff. I come from Brazil and we're know to have the most complex tax systems in the world (do a search on Google and you would understand what I am talking about - even SAP has an engine specifically created to work with our out-of-this-world tax rules). So, on the top of hierarchy you would have the more general items (for example, State, if you want people from out of state to have a different discount, for example) and go down the "tree". The formula you're going to use is the one that goes to the utmost item (further down the tree). Then you can use any expression evaluator available in the internet (there are tons of them for C# and other languages). You can even create your own language - supporting IF statements, for example - to accomplish more complicated tasks. I've done this successfully in a pretty interesting project in the company I currently work for. Hope this helps. Robson Siqueira Enterprise Architect