A state agency may pay or reimburse a state employee for a travel expense the employee incurs while using personal or compensatory leave if:
(1) the leave is used while the employee is away from the employee’s designated headquarters;
(2) the primary purpose of the employee’s being away is to conduct official state business; and
(3) the agency determines that returning the employee to the employee’s designated headquarters while using the leave would not be cost effective or would be impracticable.