@alisha-- A misdemeanor fine has to be paid! If you refuse to pay it, you can be incarcerated!
From what I know, a judge considers a person's financial situation before penalizing them with a fine. And if someone is having trouble paying it, they can always appeal to the court to extend the payment deadline or to pay it in installments. It is at the judge's discretion but I doubt that any judge would put someone under that financial responsibility if they seriously can't afford it.
I don't know for sure, but I think that a misdemeanor fine plus incarceration are rarely imposed together. Maybe if the individual has many misdemeanors on their record and the fines don't appear to be effective.