Let's assume you want to buy a refurbished laptop on sale from Dell in Texas. Further assume you live in Illinois. You would not normally pay state sales tax because this is an out-of-state sale. But, Dell has at least one franchise store doing business in the state and so, you'll be charged IL sales tax for a purchase made in TX.
However, you live next to the state line and you have a friend that lives in Iowa. You buy the refurb laptop from Dell (TX) and have it shipped to your friend in IA. No sales tax is charged.
You'll still have to pick it up in person in IA or have it shipped to you (IA to IL), but you've escaped IL sales tax. This is called flipping the rigid digit to the IL Department of Revenue.
I needed to purchase a light for my swimming pool this summer. The brick and mortar stores around here wanted well over $300. I found it on Amazon for about $240, but at the checkout they added $20 TAX. I backed out at the last minute because I didn’t remember ever being charged tax when purchasing something from Amazon before.
Then I found http://www.sunplay.com located in Utah. They had the same item for $199, with free shipping and no sales tax. Done and done. And I’m done with Amazon. I will do my online shopping with businesses that don’t make deals with the devil.