INCOME TAXES (Details) - Income Tax Rate Reconciliation - USD ($)	12 Months Ended
	May 31, 2021	May 31, 2020
Income Tax Rate Reconciliation [Abstract]
Computed "expected" tax benefit	$ 1,355,756	$ 489,651
Increase (reduction) in income taxes resulting from:
Change in valuation allowance	(2,102,000)	(1,029,000)
State income taxes, net of federal benefit	190,233	154,254
Research and development tax credits	456,388	49,770
Permanent tax differences and other	98,823	334,525
Foreign taxes of subsidiaries	(12,257)	(6,590)
Income tax expense	$ (13,057)	$ (7,390)