From the research that I have done, taxation of software sales varies from state to state and may depend on the form of delivery of the software. From the states that I looked at, there was a greater likelihood of sales tax applicability if the software was of the "off-the-shelf" variety (not custom software), but if installed through a download rather than shipped, it was not subject to sales tax. I agree with Scott - just call your state tax office and explain your situation.