The following persons are exempt from the provisions of sections 154.001, 154.002, 154.003, 154.01 to 154.161, 154.19 to 154.21, and 154.24 to 154.26 while in the proper discharge of their professional duties:
(1) persons authorized by the law of this state to practice medicine, surgery, osteopathy, and chiropractic;
(2) commissioned medical or surgical officers of the United States armed services;
(3) registered nurses, licensed practical nurses, and nursing aides performing services under the direction and supervision of a registered nurse, provided, however, that no additional compensation shall be paid for such service and patients who are so attended shall not be charged for barbering;
(4) cosmetologists, provided, however, that cosmetologists shall not hold themselves out as barbers or, except in the case of nail technicians, practice their occupation in a barber shop; and
(5) persons who perform barbering services for charitable purposes in nursing homes, shelters, missions, or other similar facilities, provided, however, that no direct or indirect compensation is received for the services, and that persons who receive barbering services are not charged for the services.