939.06  Acquitted defendant not liable for costs.--No defendant in a criminal prosecution who is acquitted or discharged shall be liable for any costs or fees of the court or any ministerial office, or for any charge of subsistence while detained in custody. If the defendant shall have paid any taxable costs in the case, the clerk or judge shall give him or her a certificate of the payment of such costs, with the items thereof, which, when audited and approved according to law, shall be refunded to the defendant.