Baffled and Befuzzled.

I'm trying to have a product that has a base price Say $29.95
a discount of 40% making it $17.97 and
a discount of 45% making it $46.47.

The only way I've been able to get this to work, even remotly, is to set the products Attribute price at -29.95 and the price factor at .6 for 40% off and .55 for 45% off.

Is there a way to set the price factor to a negative number?

Am I way off base on how I'm using the pricing of the attributes?

Thanks!!