Except as provided for in sections 471.87 and 471.88, no teacher in the public schools, nor any state, county, town, city, or district school officer, including any superintendent of schools, or any member of any school board, nor any person connected with the public school system in any capacity, shall be interested directly or indirectly in the sale, proceeds, or profits of any book, apparatus, or furniture used, or to be used, in any school with which the person is connected in any official capacity. Any person violating any of the provisions of this section shall forfeit not less than $50, nor more than $200 for each such offense. This section shall not apply to a person who may have an interest in the sale of any book of which that person is the author. Nothing in this section shall prohibit the spouse of an employee or officer covered by this section from contracting with the school district for the sale or lease of books, apparatus, furniture, or other supplies to be used in a school with which the employee or officer is connected in any official capacity, as long as the employee’s or officer’s position does not involve approving contracts for supplies and the school board unanimously approves the transaction.