Subject to subsection (b) of this section, the legislative body of a participating governmental unit may withdraw from participation in a State system and transfer to a local pension system or another State system any of the following groups of employees of the governmental unit who consent to the withdrawal, and who qualify for membership in the State system or local pension system: all employees of the participating governmental unit; fire fighters; law enforcement personnel; detention center officers; or subject to the approval of the Board of Trustees, a homogeneous unit of at least 10 employees. A participating governmental unit may withdraw from participation in a State system only if: the new State system or local pension system of the participating governmental unit requires member contributions at the same rate as the member contribution rate applicable to employees of the participating governmental unit in the State system from which the participating governmental unit is withdrawing; or the participating governmental unit: does not provide for the employer pickup of member contributions to the current State system of the participating governmental unit within the meaning of § 414(h)(2) of the Internal Revenue Code; and certifies that it will not become an approved employer under § 21–313 of this article on or after the effective date of participation in the new State system or local pension system.