Multiply by 50 states, and it's up to 25 hours a month of work.
For those of you who have never done this, sales taxes are a lot more complicated than they seem. In the three states where I've had retail businesses, different types of products have different sales taxes and each has to be reported individually.
It gets exponentially more complicated if your state also has use, consumption, or other retail taxes; and if it requires you to report purchases your company made out of state.
If I had a popular company, even with small sales, I could easily see this becoming a week-long headache I offload onto my accountant, who will then charge me extra.
So not only do I have to raise prices to include the sales tax for various states, I have to factor in the extra accounting expense.