When any motor carrier fails to file a report within the time prescribed by this chapter for the filing thereof, the motor carrier shall pay as a penalty for each day thereafter, Saturdays, Sundays and other legal holidays excluded, until the report is filed, the sum of $5.75, up to a maximum penalty of $28.75 for each such report. For each report filed more than 5 business days late, the penalty shall be $28.75 or 12 percent of the tax due, whichever is greater, for each such report. In addition to the penalty imposed by this section, any unpaid tax shall bear interest at the rate of 1% per month, or fraction thereof, until the same is paid. The penalties and interest charges imposed by this section shall be paid to the Department of Transportation in addition to the tax due. The Department of Transportation, if satisfied that the failure to file the report or pay the tax was excusable, may remit or waive the payment of the whole or part of the penalty or interest charge assessed.