(a) None of the license fees provided for by this chapter shall be so applied as to occasion an undue burden upon interstate commerce. In any case where a license fee is believed by a licensee or applicant for a license to place an undue burden upon such commerce, he may apply to the Mayor for an adjustment of the fee so that it shall not be discriminatory, unreasonable or unfair as to such commerce. The application may be made before, at or within six months after payment of the prescribed license fee. The applicant shall, by affidavit and supporting testimony, show his method of business and such other information as the Mayor may deem necessary in order to determine the extent, if any, of such undue burden on such commerce. The Mayor shall then conduct an investigation, comparing the applicant's business with other businesses of like nature and shall make findings of fact from which he shall determine whether the fee fixed by this chapter is unfair, unreasonable or discriminatory as to the applicant's business and shall fix as the license fee for the applicant, an amount that is fair, reasonable and nondiscriminatory or, if the fee has already been paid, shall order a refund of the amount over and above the fee so fixed.
(b) In fixing the fee to be charged, the Mayor shall have the power to base the fee upon a percentage of gross sales, or any other method which will assure that the fee assessed shall be uniform with that assessed on businesses of like nature, so long as the amount assessed does not exceed the fees as prescribed in Section 725.05. Should the Mayor determine the gross sales measure of the fee to be the fair basis, he may require the applicant to submit, either at the time of termination of the applicant's business in the Village or at the end of the amount of fee therefor, provided that no additional fee during any one calendar year shall be required after the licensee has paid an amount equal to the annual license as prescribed in Section 725.05.