In general, states tax the purchase of so-called "tangible goods," but there are often a laundry list of exceptions. For example, in New Jersey all clothing is tax-free. Meanwhile, clothing items and footwear that cost less than $110 are not taxed in New York.
Want to buy an American flag to hang outside? Some states like Connecticut and Wisconsin won't charge a tax on American or state flags, for that matter.
Prescription medications or grocery products, like milk or raw chicken, are often tax-free but other food products, such as prepared food or junk food, will often get hit.
What about digital music, streaming movies and e-books?
Like other products, the Marketplace Fairness Act wouldn't create any new taxes on so-called "digital goods," but it would let states enforce the laws they have in place already.
Washington state, for example, has a digital goods sales tax that applies to everything from streaming music and movies to e-books. Florida, meanwhile, taxes streaming video but not digital books.
Many sellers already collect these taxes. For example, if you live in Washington, where Amazon.com is based, you're already paying tax on digital purchases. Apple already collects sales tax for iTunes purchases in states where digital music is taxed, according to its website. And Netflix also already collects tax where applicable.
To find out what items are taxed in your state and at what rate, contact your state's tax and revenue agency. A map with links to the 50 state tax websites can be found here.