Stuff you buy at Amazon is actually most of the time from 3rd party sites. Typically if the item is purchased for a company that is in the same state as the receiver sales tax is charged. Not sure if the non-tax would apply but below is the footnote on the Amazon site.
Of note the non-tax weekend in Florida computers purchased for personal use are tax free for the first 750.00 of the price.
Unless otherwise noted, items sold by Amazon.com LLC are subject to sales tax in select states in accordance with the applicable laws of that state. If your order contains one or more items from a seller other than Amazon.com LLC, it may be subject to state and local sales tax, depending upon the seller's business policies and the location of their operations.
We do not collect sales or use taxes in all states. For states imposing sales or use taxes, your purchase is subject to use tax unless it is specifically exempt from taxation. Your purchase is not exempt merely because it is made over the Internet or by other remote means. Many states require purchasers to file a sales/use tax return at the end of the year reporting all of the taxable purchases that were not taxed and to pay tax on those purchases. Details of how to file these returns may be found at the websites of your respective taxing authorities.
Please note: The sales tax indicated on the checkout form is an estimate. The sales tax ultimately charged to your credit card will be calculated when your credit card charge is authorized and will reflect applicable state and local taxes.