Every approved school shall be subject to examination by the state auditor for the sole purpose of determining whether such school has properly certified eligibility and enrollment of students and credited grants paid on behalf of such students. However, nothing in this subpart shall be construed to interfere with the authority of such school to determine admissibility of students or to control its own curriculum, philosophy, purpose, or administration. In the event it is determined that a school knowingly or through error certified an ineligible student to be eligible for a grant under this subpart, the amount of the grant paid to the school pursuant to such certification shall be refunded by the school to the authority.