Brandon Notices

I'm at Cost Plus, where they have many signs boasting their furniture sale. They all say, "All furniture up to 50% off." However, most of the furniture isn't fully half off. The sofa I'm sitting on is only 20% off. Since "up to 50%" means that the discounts can be less than half off, why don't they just take the extra step and make the signs read, "up to 100% off"? It sounds much more impressive, and isn't any more misleading.