I personally think that Traditionally, businesses that have a tax presence in a state (called a tax nexus) must collect, report, and pay sales taxes on items they sell which the state lists as taxable. For example, if you sell clothing in Iowa, you must collect sales tax from your customers, then report to the state and pay the amount collected, according to Iowa law. While some states don't have sales taxes, most do. Check with your state's taxing authority for more information on what's taxable in your state and how to register.
I do not believe Amazon will lose business now that customers have to pay sales tax. I believe customers have simply been taking advantage of tax free shopping knowing that it would come to an end one day. I believe customers are aware that this change is part of the government catching up and nothing to do with the company.
No, Amazon will not lose business now that customers have to pay sales tax, because people primarily buy things off of Amazon because they are hard to find in box stores. They also buy on Amazon because it is convenient to sit and shop and home. People will forget about the sales tax.
The big scare of imposing sales tax on Amazon was that customers would move their business back to standard brick and mortar stores because the prices would now be just as competitive. That's wrong. Brick and mortar stores have overhead that just isn't involved with online sales. The reason Amazon does so well is because of that. Their customers will not be lost. They may lose some foreign suppliers that can no longer guarantee some price gouging, but aside from that, the market is still in demand.
Most people are unhappy to hear that Amazon will be charging sales tax, but I don't believe that they will stop shopping at Amazon. I did some Christmas shopping at Amazon, and I forgot all about the sales tax until I saw it mentioned on the final page of the checkout process. After spending so much time researching and choosing my items, I wasn't about to cancel the sale for the sake of a few dollars. Amazon's discounts make up for the sales tax and more, anyway.