(1) The normal rate of contribution of members shall be those adopted by the board of administration, subject to the approval of the city council or city commission, and for the first five-year period such rates shall be based on sex and on age of entry into the retirement system, which age shall be the age at the birthday nearest the time of entry into the system. The rates so adopted shall remain in full force and effect until revised or changed by the board of administration in the manner provided in RCW 41.28.060. The normal rates of contribution shall be so fixed as to provide an annuity which, together with the pension provided by the city, shall give as nearly as may be a retirement allowance at the age of sixty-two years of one and one-third percent of the final compensation multiplied by the number of years of service of the retiring employee. The normal rate established for age sixty-one shall be the rate for any member who has attained a greater age before entry into the retirement system. The normal rate of contribution for age twenty shall be the rate for any member who enters the retirement system at an earlier age.

(2) Subject to the provision of this chapter, the board of administration shall adopt rules and regulations governing the making of deductions from the compensation of employees and shall certify to the head of each office or department the normal rate of contribution for each member provided for in subdivision (1) of this section. The head of the department shall apply such rate of contribution, and shall certify to the city comptroller on each and every payroll the amount to be contributed and shall furnish immediately to the board a copy of each and every payroll; and each of said amounts shall be deducted by the city comptroller and shall be paid into the retirement fund, hereinafter provided for, and shall be credited by the board together with regular interest to an individual account of the member for whom the contribution was made.

Every member shall be deemed to consent and agree to the contribution made and provided for herein, and shall receipt in full for his or her salary or compensation. Payment less said contribution shall be a full and complete discharge of all claims and demands whatsoever for the service rendered by such person during the period covered by such payment, except his or her claim to the benefits to which he or she may be entitled under the provisions of this chapter.

(3) At the end of each payroll period, the board shall determine the aggregate amount of the normal contributions for such period, and shall certify such aggregate to the city comptroller, who shall thereupon transfer to the retirement fund, hereinafter provided for, from the money appropriated for that purpose in the budget for the fiscal year, an amount equal to the aggregate normal contributions for the period received from members.

(4) Any member may elect to contribute at rates in excess of those provided for in subdivision (1) of this section, for the purpose of providing additional benefits, but the exercise of this privilege by a member shall not place on the city any additional financial obligation. The board of administration, upon application, shall furnish to such member information concerning the nature and amount of additional benefits to be provided by such additional contribution.