Note 2 - Significant Accounting Policies - Schedule of Earnings Per Share (Details) - USD ($)	3 Months Ended		9 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Net income applicable to common shareholders	$ 941,405	$ 626,586	$ 2,467,068	$ 2,511,049
Weighted average shares, basic (in shares)	19,019,000	19,555,000	19,255,000	19,511,000
Warrants to purchase common stock (in shares)	403,000	387,000	324,000	233,000
Weighted average shares, diluted (in shares)	19,422,000	19,942,000	19,579,000	19,744,000
Basic (in dollars per share)	$ 0.05	$ 0.03	$ 0.13	$ 0.13
Diluted (in dollars per share)	$ 0.05	$ 0.03	$ 0.13	$ 0.13