CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($)	9 Months Ended
	Feb. 28, 2022	Feb. 28, 2021
Cash flows from operating activities:
Net loss	$ (2,772,023)	$ (5,735,033)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	102,272	94,550
Change in allowance on accounts receivable	(817,122)	578,438
Inventory reserve	270,805	1,437,547
Stock option expense	959,368	1,022,320
Amortization of right-of-use asset	189,696	173,919
Changes in assets and liabilities:
Accounts receivable	1,113,435	(690,691)
Inventories	(295,980)	(1,446,766)
Prepaid expenses and other	(296,839)	734,966
Reduction in lease liability	(180,637)	(156,384)
Other assets	117,171	(114,664)
Accounts payable and accrued expenses	2,025,460	(230,575)
Accrued compensation	148,388	88,309
Advances from customers	3,213,052
Net cash provided by (used in) operating activities	3,777,046	(4,244,064)
Cash flows from investing activities:
Increase in intangibles	(113,436)	(116,881)
Purchases of property and equipment	(32,547)	(106,760)
Net cash used in investing activities	(145,983)	(223,641)
Cash flows from financing activities:
Proceeds from sale of common stock, net	2,317,160	1,011,475
Proceeds from exercise of stock options	39,175	96,455
Net cash provided by financing activities	2,356,335	1,107,930
Effect of exchange rate changes in cash	(12,901)	(8,687)
Net increase (decrease) in cash and cash equivalents	5,974,497	(3,368,462)
Cash and cash equivalents at beginning of period	4,199,311	8,641,027
Cash and cash equivalents at end of period	10,173,808	5,272,565
Cash paid during the period for:
Income taxes	13,334	13,730
Non-cash investing and financing activities:
Increase in right-of-use asset due to lease extension or establishment	4,478
Increase in lease liability due to lease extension or establishment	$ 4,478