The sale agreement shall provide for:

(1) Annual payments of not less than 20 percent of the cost of the voting machines or vote tally systems or computers or computer systems, plus interest, payable on or before December 15.

(2) Payment by the county of maintenance, supplies, storage and transportation costs of the voting machines or vote tally systems or computers or computer systems. [Formerly 258.415; 1985 c.808 § 1; 1995 c.144 § 16]