An employee of a ``retail or service establishment'' who is paid on
a commission basis or whose pay includes compensation representing
commissions need not be paid the premium compensation prescribed by
section 7(a) for overtime hours worked in a workweek, provided the
following conditions are met:
(a) The ``regular rate'' of pay of such employee must be more than
one and one-half times the minimum hourly rate applicable to him under
section 6, and
(b) More than half his compensation for a ``representative period''
(not less than one month) must represent commissions on goods or
services.