The secretary is authorized to pay a reward, out of money appropriated from the Motor License Fund for the purpose, to any person, other than a State officer or employee, who reports a distributor who has failed to file the reports required and pay the tax imposed by this chapter. The reward shall be in an amount the secretary deems proper, not exceeding 10% of the amount of the tax, penalty and interest due. A reward shall not be paid unless collection of the delinquent tax has been made or the distributor has been convicted for violating this chapter.