Can a county tax office refuse payment of a $10 fee with a $100 bill claiming they do not have to make change?

Like "The Master" stated, the 100 bill IS legal tender and by law cannot be refused to settle a debt.

However, some points worth noting. If the payment and the service provided are roughly at the same time (like for example a bus fare, or vending machine purchase for a chocolate bar) than there is no obligation to provide change.

Similarily, if there are signs stating large bills not accepted at certain times (in order to minimize robberies), that too is okay.

But if you had waited for the copies to be made and took receipt of them, AND then paid the $100 bill, the gov't agency would be forced to accept it and make change for you.

Hello -- why would you only have a $100 on you. That is silly.

You cannot expect any business to have change at any given time equal to that amount. They could not make change at that time. There is nothing wrong with this. They told you to come back later with a smaller bill. The person in front of you may have taken all their change, or may have paid for a more expensive item.

Why should they keep enough cash on hand to deal with idiots who can't bring smaller bills with them. They probably don't do a lot of cash business at all.

While the $100 is legal tender, I know of no law indicating that they are required to accept it. Would you have preferred that you pay them the $100, and just receive $50 cash back because that was all they had?

No because the money says on it:

This note is legal tender for all debts, public and private.

By doing so, they are going over US law unless they physically don't have the money there to provide the change and thus can't.

yes, many government agencies do not keep money available to make change.

They are not refusing payment they simply require, exact payment

Sorry, good luck