A majority of all the members of the commission shall constitute a quorum to do business, but a lesser number may adjourn from time to time and compel the attendance of absent members in such manner and under such penalties as may be prescribed by ordinance. The affirmative vote of a majority of all members of the commission shall be necessary to adopt any ordinance, resolution, or order; except that a vote to adjourn, or an action regarding the attendance of absent members, may be adopted by a majority of the members present. No member may be excused from voting except on matters involving the consideration of his/her own official conduct or when his/her financial interests are involved.