[ghaff]

>Breaking out sales tax has caused a 9% sales drop in states Amazon charges sales tax in.

Note it's really "collects" sales tax in. Buyers still, in principle, owe use taxes on the purchase--which individuals often don't pay of course.

I don't think it's so much a matter of whether sales tax is bundled or not though. For big ticket electronics purchases, for example, the same item is often available for the same price with "free" shipping from other online resellers who don't collect sales tax--and is cheaper for many consumers as a result.