News flash...the US Supreme Court has just ruled that states (and local governments?) can demand tax collection on all internet sales.
Within the USA, there are 45 states and 10's of thousands of local governments who impose sales tax; each at different rates and with different protocols related to how they collect the tax. As an online retailer, you may now be obligated to collect these taxes for online sales, and see that each of these taxing entities get their money.
Stand by...as this story develops, expect many online sales facilitators (eBay, Etsy, etc...) and literally millions of small business operators to go under.
Personally, I have no idea how to collect, much less disburse, sales tax related to all these taxing entities.