None of the license taxes provided for by section 5.04.160 of this chapter shall be applied as to occasion an undue burden on interstate commerce. In any case, where a license tax is believed by a licensee or applicant for license to place an undue burden upon such commerce, he or she may apply to the license assessor and collector for an adjustment of the tax so that it shall not be discriminatory, unreasonable or unfair as to such commerce. Such application may be made before, at or within six (6) months after payment of the prescribed license tax. The applicant shall, by affidavit and supporting testimony show his or her method of business and the gross volume or estimated gross volume of business and such other information as the license assessor and collector may deem necessary in order to determine the extent, if any, of such undue burden on such commerce. The license assessor and collector shall then conduct an investigation, comparing applicant's business with other businesses of like nature and shall make findings of facts from which he or she shall determine whether the tax fixed by section 5.04.160 of this chapter is discriminatory, unreasonable or unfair as to applicant's business and shall recommend to the city council a license tax for the applicant in an amount that is nondiscriminatory, reasonable and fair, and if the city council is satisfied that such license tax is the amount that the applicant should pay, it shall fix the license tax in such amount. If the regular license tax has already been paid, the city council shall order a refund of the amount over and above the tax fixed by the city council. In fixing the fee to be charged, the license assessor and collector shall have the power to base the fee upon a percentage of gross sales, or employees, or may use any other method which will assure that the fee assessed shall be uniform with that assessed on businesses of like nature. (Prior code § 9-125)