Sales Tax Issue

Firstly, thank you to anyone that answers this for me.

Ok, here is my issue. I bought a car in NJ recently for $1,450. The sales tax for NJ is 7% which comes out to $101.50 that I owe. I went to the DMV, paid the $101.50 and I have a receipt for that as well. Weeks later I get a letter stating that I did not in fact pay the due sales tax and that only $35.00 for applied to it and the other $66.50 went to the DMV for fees (plate, title, ect.) My question is simple. Am I obligated to pay the DMV the $66.50 so that they can pay the state the due sales tax or should the DMV be footing the bill because they made the error in the first place? I am a bit of a conservative so I see it like this, if I walk into a store and buy a loaf of bread for $5.00, pay the clerk $5.00 and get a receipt showing that I payed $5.00, shouldn't the store or store clerk eat the sales tax they forgot to charge me instead of sending me a bill for the rest?

Thank you for any responses.

You legally still have to pay it if you agree it was a mistake.

Thanks for the info. I am not worried about the money issue, as it is a small amount and a non-issue. I am trying to focus more on the point I guess.

Thanks again.