If any producer or handler that is duly assessed pursuant to the provisions of this chapter fails to pay to the director the amount so assessed on or before the date which is specified by the director, the director may add to such unpaid assessment an amount not exceeding 10 percent of such unpaid assessment to defray the cost of enforcing the collection of such unpaid assessment. In addition to such payment for the cost of enforcing such collection, any such producer or handler shall pay to the director a penalty of 5 percent for each 30 days of the unpaid balance for each 30 days the assessment is unpaid, prorated over the days unpaid, commencing 30 days after notice has been given to such producer or handler of his failure to pay the assessment on the date required, unless the director determines, to his satisfaction, that such failure to pay is due to resonable cause beyond the producer’s or handler’s control. Such penalty shall not exceed 50 percent of the total amount of the assessment due.