Oh please no. I hate haggling. My time shouldn't be spent worryin if I left 10% on the table. This is the reason Amazon is killing eBay, and now they to introduce the same tired tactics.
So amazon is borrowing from ebay and ebay is borrowing from amazon.
This is a personality... um... "quirk" on your part.
It's not that different from playing poker, it's just more informal.