I know I am late to notice, but I just realized the promoted listing fee is calculated including both shipping and sales tax.
While I understand some overcharge for shipping, or would if it would escape fees, and can kind of understand charging for the shipping costs (not really, since we buy the labels thru eBay), I can find no justification on being charged a percentage of their taxes paid.
Seems a vast overcharge to sellers. Not even really sure its legal.