Yeah, that's a big selling point and probably why I'm going to hold off.
I'm in MA and I don't think I would have to pay tax. I should know but I don't.
I'm in MA too and you have to pay sales tax when you buy from Canon. I usually go through Mr Rebates and get 3% cash back which helps offset it.
That being said, I bought from Big Value when they had their first big 5D3 sale and had zero issues.