The Supreme Court just handed down a decision in South Dakota v Wayfair, Inc. that states can force online retailers to collect sales taxes from purchases. This overturns a decision from 1992 that mandated that states could levy taxes on businesses only if they had a brick-and-mortar presence within that state's borders.
While this ruling is beneficial to state governments, it stands to have a negative impact on retailers and consumers alike. Part of the draw to buying things online, aside from the convenience, was avoiding sales tax (assuming you bought from a smaller merchant), which on more expensive products could cost more than shipping — that's not to mention the possibility of free shipping in some cases, too. But paying online sales tax is nothing new, especially if you buy from large stores like Amazon, Walmart, Dell, and so on.
Honestly, this shouldn't be surprising to anyone, but it's a bummer nonetheless. States have been trying to get this fixed for several years, especially as online retail has encroached on brick-and-mortar sales.