Every employer insured in the Government Insurance Fund shall keep a true and accurate record of the number of his employees and of the wages paid by him, and such records shall be open to inspection at any time by the Administrator and by the Commissioner of Finance. Any employer who fails to keep true and accurate records or who wilfully misrepresents the amount of the payroll upon which the premium chargeable is based shall be liable to a fine of five times the amount of the difference between the premium paid and the premiums which should have been paid, and the Commissioner of Finance shall assess and collect said fine in the same manner as premiums are assessed and collected.