Any licensee, except in the case of a revoked license, shall be entitled to a rebate of part of the fee paid if the license is surrendered before it expires. The amount of the rebate shall be determined by dividing the total license fee by the number of days for which the license was issued and then multiplying the result by the number of full days not expired. In all cases, at least $5.00 of the original fee shall be retained by the City to cover administrative costs.