The grantee shall cause to be paid all proper invoices submitted to it after procurement of the performance of any project work. All costs charged to the project shall be supported by properly executed payrolls, time records, invoices, contracts, or vouchers evidencing in detail the nature and propriety of the charges. For the purpose of payment, the grantee shall require an invoice evidencing:
Ill. Admin. Code tit. 71, § 41.75