Is the 9/10 cent added to the price of gas necessary?

I was trying to find out the history of the 9/10 portion of gas prices, when I came upon a site that has a lot of information - maybe too much! Check it out, and then tell me what your take on it is. Heck, tell me it's origin. I still am not sure. I personally think it is time to eliminate the 9/10 portion of the gas price. With the high price of gas today, is the 9/10 portion really necessary???

http://www.users.qwest.net/~taaaz/AZgas.html