The Secretary shall provide for the testing of all equipment used in the sampling, grading, inspection, and weighing for the purpose of official inspection, official weighing, or supervision of weighing of grain located at all grain elevators, warehouses, or other storage or handling facilities at which official inspection or weighing services are provided under this chapter, to be made on a random and periodic basis, under such regulations as the Secretary may prescribe, as the Secretary deems necessary to assure the accuracy and integrity of such equipment. Such regulations shall provide for the charging and collection of reasonable fees to cover the estimated costs to the Secretary incident to the performance of such testing by employees of the Secretary. Such fees shall be deposited into the fund created by section 79(j) of this title.