How to apply State Department tax exemption certificate on Apple's website?

I am a holder of a State Department tax exemption certificate and I am wondering whether, and if so then how, I can be exempted from taxes on orders placed through apple's website.

Is it still the case that you can send an email to salestax@apple.com after placing an order to request a tax refund, or is it something that can be done only at an Apple Store?

Any help would be highly appreciated.

[Re-Titled by Moderator]