A merchant who is serious about merchandising specials and sales and deals (not just discounts, but also gift with purchase, category or product specific grouping offers, etc...) MUST look at THE premier module for merchandising....
Altered Cart - On Sale :: Promotions, Sales & Specials
This mod can do just about anything. And if it can't do it stock, you can still probably find a way.
Use OnSale with a 1st-class banner system, and your merchandising options are pretty much endless.
This NOT to be confused with the mod from X-Cart with an identical name. AlteredCart's OnSale mod came first, and has been upgraded over the years with even more features. X-Cart poached the name and forced Altered Cart to rewrite their entire mod, because Xcart used the IDENTICAL table and variable names. It was a PITA for me too -- since when I upgraded from 4.1.9 to 4.5.4, I had to purge all old references and rebuild all sales....
But that's old news...
Bill @ Altered Cart offers incredible support and you will not be disappointed with OnSale.