If a tenant proposes to use a federal, State, or local program to assist the purchase, for either mortgage insurance, a mortgage guarantee, or a direct mortgage, the required deposit shall not exceed the cash contribution required of the buyer by that program. If no such program is involved in the tenant purchase, the deposit required for a sales contract shall be at least 1% of the purchase price. No landlord may refuse to enter into a sales contract with a tenant solely because the tenant proposes to use a federal, State, or local program to assist in the financing of the purchase. A sales contract shall contain a reasonable financing contingency clause which:shall not require the tenant to obtain financing in less than 60 days from the date a contract is tendered by the landlord; and shall excuse the tenant from performance of the sales contract if the tenant is unable to obtain adequate financing within said 60-day period.