Saturday shall be a legal holiday throughout each year for all elective and appointive officials, deputies, clerks and other employees of the State, except members of the State Police, employees of the Department of Safety and employees assigned to rotating and shift work. Saturday shall be a holiday for employees of the Department of Safety throughout the year excepting the last 2 Saturdays of each quarter. During the periods stated, state offices affected hereby shall not be open for business on Saturdays.