On your site I see 8% 20% 25% 27% discounts ...

Are you using Sales as in Sale Maker or Specials? Or what to manage these?

What are the exact settings on your Sales made with Sale Maker?

What Category or Category categories_id are you putting on Sale?

Are the Products setup that the Category on Sale with Sale Maker is the Product's master_categories_id if you use Linked Products?