All participants shall pay an additional 10% fee of the cost of rental space or stall to the proprietor. In the event the 10% additional fee is less than $.50 per rental space or stall, a minimum fee of $.50 shall be collected by the park and swap meet proprietor. All such fees shall be payable at the same time as the rental fees prescribed by the swap meet proprietor. All 10% fees are to be paid to the City on or before the fifteenth day of the following month for the preceding month. (Prior Code, § 8-3-2)