eBay enables a seller to offer various kinds of shipping cost discounts on orders (items purchased separately from the same seller and now combined for payment and shipping).
The kind of discount that an item can receive in that order is determined by what shipping cost discount profile was assigned to the item when it was listed, and, if the seller defined a global promotional discount and it was in effect at the time the order line item was created, the order can also benefit from a promotional discount. The discounts "applied to the item" are only realized when the item is combined in an order—no shipping discount is applied to the item if it the item is purchased and shipped by itself.
A user can also offer a packaging/handling cost Shipping Discount for Combined Invoice orders.