Okay, it's not really a scam... but it does involve a bit of psychology used against the shopper... How often have you gone to the store for a much-needed item only to be faced with a sign that says "Two for $5"? The first thing I always wonder is whether I can get one for $2.50, or if I have to buy two of them to get that sale price.

That's what the store is hoping you wonder, and that you'll buy two just to be on the safe side of the sale. It's all marketing and psychology, and quite often, the sale price is valid whether you buy one or two. The store is trying to move volume. So instead of telling you that your personal care item is on sale for $2.50, they are going to offer you a "two for" deal. The hope is that you'll buy two instead of the one you were planning on buying.

It seems to me that I see these signs more and more often, so I'm suspecting that the psychology works in favor of the stores. Here's the thing: If you're going to use up one pretty quickly and then go to the store to buy another, it probably makes sense to scoop up two right away since they're on sale.

But if it's an item that you use sparingly, don't bother to get two. You've got your money tied up in a second item that you won't need for a long time, so it just doesn't make sense. It's actually more budget friendly to wait and buy the second one closer to when you actually need it. Besides, there's a good chance it will be on sale again before you'll need that second one. So keep your money in your pocket a little bit longer and don't end up spending more than you planned by buying that second one when you don't really need it.

Tracy L. Coenen, CPA, MBA, CFE performs fraud examinations and financial investigations for her company Sequence Inc. Forensic Accounting, and is the author of Essentials of Corporate Fraud.