Every prisoner of a county jail under a sentence to accommodate the person‘s work schedule in accordance with section 356.26 is liable for the cost of the prisoner’s board in the jail as fixed by the county board of supervisors. The sheriff shall charge the prisoner’s account for the board and any meals provided in section 356.31. If the prisoner is gainfully self-employed the prisoner shall pay the sheriff for the board, in default of which the prisoner’s privilege under this chapter is automatically forfeited. If necessarily absent from jail at a meal time, the prisoner shall at the prisoner’s request be furnished with a lunch to carry to work. If the jail food is furnished directly, by the county, the sheriff shall account for and pay over the meal payments to the county treasurer. The county board of supervisors may by resolution provide that the county furnish or pay for the transportation of prisoners employed under sections 356.26 through 356.35 to and from the place of employment. However, the charges for board and meals under this section shall not exceed fifty percent of the wages or salaries of the prisoner, after deductions required by law, including deductions to satisfy any court-ordered child support obligations, earned during the period of time for which the charges are made.