That's never been the case, they always charge tax if you're shipping address requires it.
I paid $499 for the ADC membership which gave me 20% off the MBP so if you add everything up I paid around $40 for the ADC membership which was a great deal.
I think legally apple can charge you sales tax in your state for online orders IF they have an Apple Store in that state. I remember people complaining about newegg charging shipping tax and it turned out they had offices/locations in their state.