I never even tell buyers if my shipping was higher than quoted. And there have been a few times I was way off for some reason and ate a $10-15 amount for the extra for shipping. I figure I advertised it at a certain shipping price, and I know as a buyer I factor that price into my overall cost for the item- I'll bid higher if shipping is lower. So I don't think it's fair as a seller to ask the buyer to make up for my shipping mistakes.