Thanks for the comments (love it Jeff). I agree that accounting would be a different scenario, heck, maybe even storing an OrderAdjustments table where you have an AdjustmentType (SalesTaxState, SalesTaxFederal, Shipping, Packaging, Coupon Discounts, etc.) where all amounts could be stored in positive form because the "Type" tells you what the amount is (+ or -) (even though I would personally store those as +/- values).

However, in the situation I am in, I do agree that the UI should make it easy on the user, but store it in one column as positive or negative amount. However, I've already lost the battle because "We don't know what future requirements will be...", really? So it's fun to just hear all the other lame requirements out there.