This is just a quick question for the developer (or anyone else familiar with tax laws)

I was about to purchase the iPLM until it showed that I am being charged a tax. My loose understanding is that one cannot charge tax (especially for out of state transaction) when there is not a tangible/physical good involved. For example, if I were buying a boxed software DVD, which is also available in my state (say, from a physical store), then I can be charged a tax. I'm not sure if this is a physical goods issue or an out-of-state issue, but since I had never been charged a tax before under similar circumstances (buying software sold only online, from outside my state [MN]).

I hope I don't sound accusatory; I am genuinely curious how this works.

I appreciate any input! Thank you.