tangor - 11:28 pm on Mar 8, 2010 (gmt 0)
The difference is Internet sales can be "tracked" better than mail order... one of the reasons why sales tax is not collected (USA) for interstate sales. All sales are subject to sales tax. Additionally most states require a minimum Use or Property tax (should the item fall in that category).
Just because mail order and internet has managed to duck the sales tax thus far does not mean it will last forever. And I'm not all that happy with Amazon ducking this issue by dropping states like Colorado, Hawaii, California... instead of meeting it head on for legislative resolution.
Taxes will eventually be collected and they will not be 5%... coming to your website in the not-too-distant future.