I'm really not sure what the guidelines are for loose tobacco. I know the Smoke Shop in town stocks bags of tobacco from India. I looked at the label: made in India, packaged in New Jersey.
So, India ships over the tobacco leaves, a place in New Jersey chops it up and bags it and sends it out for distribution. There is no tax on the bag. Just a 25 cent surcharge.
Each state is different regarding the taxes on various tobacco products (OTP) but there are both federal and state taxes on the loose tobacco, it is just not as onerous or obvious as the taxes on cigarettes.