In the interpretation of this Chapter, the following rules shall govern:
(a) Parking spaces for other permitted or conditional uses not listed in this Chapter shall be determined by the Planning and Zoning Commission.
(b) Fractional numbers shall be increased to the next whole number.
(c) Where floor area calculations are relevant to determine parking space requirements under this Chapter, and except as otherwise provided herein, "usable floor area" shall be employed as the standard.