Promotion types are returned by the PromotionCategory element and include:
ForEachQuantityXGetQuantityFreeX —When you purchase a specified number of items you
receive some number of the same items for free. For
example, for every six dozen eggs you buy you get a
dozen eggs free.
BuyAmountXGetSimpleShippingFreeX—The item is shipped free of charge.
BuyAmountXGetAmountOffX—For a specified dollar amount you receive a discount off another item. For example, buy three balls and get 25% off of a baseball glove.