Sales Tax on dowloaded map software in Arizona?

I was going to purchase the lifetime Map updates until I got to the
checkout page and found that I was being charged an $8.37 sales tax.
Has anyone else had this happen and why do they charge it?
Thanks
Jim

They don't charge it, they collect it. They collect it either because your
state demands they do it (usually due to having some sort of a legal
presence in the same state), or a mistake.

Companies don't charge sales tax, they collect it. If a company has a
"presence" in your state, they are obligated to collect the tax on sales in
that state. By presence, it only has to be a one person sales office. Some
companies collect the tax anyway, just to stay on the good side of the DOR
and avoid hassles. Even if they did not collect the tax, you'd have to
claim it on your Use Tax form so Garmin was nice enough to save you the
trouble.