eBay

I am looking at some transactions, I am selling books and ebay takes about 15% on the TOTAL sale which includes postage. As the USPS has a minimum postage rate, and some books are selling for very cheap, below the postage rate, it turns out I am losi...

Ebay charged me $2.00 more in postage than the seller, although all the information was unchanged. Why would they do that?