Leasehold interests assessable under §67-5-502 shall be valued by discounting to present value the excess, if any, of fair market rent over actual and imputed rent for the leased premises, for the projected term of the lease, including renewal options. As an alternative in valuing an interest in residential property, the interests assessable under §67-5-502(d) may be valued by the sales comparison approach using sales or transfers of similar interests in residential property. By virtue of the speculative nature of valuation of options to purchase, any option that the lessee may be given to purchase the leased premises shall be deemed to have no value. The state board of equalization is authorized to promulgate rules governing the procedure for these valuations.