COMMITMENTS AND CONTINGENCIES (Details) - Supplemental cash flow information related to leases - USD ($)	12 Months Ended
	May 31, 2021	May 31, 2020
Supplemental cash flow information related to leases [Abstract]
Operating cash flows from operating leases	$ 320,606	$ 311,742
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 79,159
Weighted average remaining lease term (in years)	5 years 98 days	6 years 98 days
Weighted average discount rate	6.50%	6.50%