Condensed Consolidated Statements of Income - USD ($)	3 Months Ended		6 Months Ended
	Nov. 30, 2020	Nov. 30, 2019	Nov. 30, 2020	Nov. 30, 2019
Income Statement [Abstract]
Sales, net	$ 4,717,597	$ 7,702,425	$ 10,477,054	$ 13,411,064
Cost of goods sold	4,141,209	5,060,703	8,346,098	9,086,465
Gross profit	576,388	2,641,722	2,130,956	4,324,599
Selling, general and administrative expenses	1,246,204	1,526,327	2,609,407	2,816,858
Operating income	(669,816)	1,115,395	(478,451)	1,507,741
Other income, net	1,470,106	26,611	1,479,752	63,842
Income before provision for income taxes	800,290	1,142,006	1,001,301	1,571,583
Provision for income taxes	155,000	225,000	180,000	300,000
Net income	$ 645,290	$ 917,006	$ 821,301	$ 1,271,583
Basic and diluted earnings per common share	$ 0.19	$ 0.26	$ 0.24	$ 0.37