Every person who engages in any business within this City which is subject to tax under the provisions of this title shall be deemed to be engaged in a separate business at each branch establishment or location at which he engages in business and must obtain a separate registration certificate and pay a separate business tax for each classification of business engaged in at each location or branch establishment in the City at which or from which the business activities classified and subject to tax under the provisions of this title are carried on. Each registration certificate so obtained and the payment of the applicable tax for each such classification of business at each such location shall authorize the person named upon the certificate to engage only in the business specified at the location for which the certificate has been issued; provided that where business is engaged in from one or more locations outside the City, only one registration certificate for each classification of business need be issued to the person for engaging in that business in the City from all such outside locations; provided further, that warehouses and distributing plants located in the City used in connection with and incidental to a business for which a registration certificate has been issued to an address located within the City shall not be deemed to be branch establishments or separate locations; provided, however, that any person conducting two or more types of businesses at the same location may, at his option, in lieu of paying a separate business tax and obtaining separate registration certificates as otherwise provided in this section, combine the activities of all such businesses and pay a combined business tax calculated under the schedule that applies to the principal business being so conducted and obtain a single registration certificate for all such businesses. (Ord. 2170 § 6, 1977: Ord. 2062 § 2 (part), 1975).