Look for clearance and you will see the departments under that column.
Once there you will notice they are offerring special shipping of .99 cents on some of the clearance merchandise that have the icon THIS ITEM SHIPS FOR 99 CENTS (ex. clothing). Other items such as household items do not have this icon for the .99 cents shipping with code 99cents.
Find an item in clearance that you want but dont want to pay shipping on. Simply place it in your cart. Next find yourself an item that says THIS ITEM SHIPS FOR 99 CENTS. Place it in your cart. Make sure it something you want to buy because you will be charged for it. Next add the code 99cents at checkout. You will then see before you finalize your order that you did indeed get the other item with the hefty shipping costs credited to your order and your order then ships for .99 cents.