Ahh, I actually didn't know about the Margin Warning by Percent. Awesome feature, I am going to check it out.
Also ausad178 in V14 you can allow up to 2 discounts for overall percentage off, and they cannot be combined or doubled up either which is nice. No more someone hitting 10% off to get an item free. Like Ronald said, you can set the product to have different prices from editing the Product in Product Control and setting the different prices, then change your security settings so they have to sign in for it so you could potentially track who is doing too much discounting as well.