Need help...Sale price changes when added to cart

Hello. Our site www.LynnLingerie.com uses ZenCart 1.3.8a. We currently have a sale of 20% off all products. The correct price is showing up on the website product pages, but when a customer adds the product to the cart it jumps the price up. For example, item 4876X is $32.66 at 20% off and when added to the cart the price jumps to $35.44 instead of stayig at 32.66. We have had numerous sales in the past and never had this issue. Any help would be appreciated!