my question is in regards to STATES TAXING INTERNET PURCHASE OF
CIGARETTES, in particular for the state of MICHIGAN. Why only
cigarettes and not all internet purchases, and
can STATES prosecute such purchases, and are they doing so.

- Because in general, there is sales tax on cigarettes? because the
state would like to discourage smoking, that later costs the system
much more in damages?

It isn't the sales tax, it is the tobacco tax, just like in most othe places:

http://www.detnews.com/2005/politics/0501/06/politics-46942.htm

The justifications for tobacco taxes  - and also taxes on gasoline - 
are some of the most hypocritical examples of taxation.  The
politicians all argue that higher taxes will reduce smoking or
unnecessary driving  - good for health and the environment -  but
calculate and budget that this will increase tax revenues.

I believe some countries are trying to take legal action (internet
cigarette selling is not limited to the States).  I don't know about
the States.

Maybe a researcher with ready knowledge of the scene can answer that.