Currency exchange by a legal entity: how to lower the conversion fee?

When to take a dollar? IN 2021 G. from April to June, the value of the American currency against the ruble fell by eight percent (with 77,9 – 4 April to 71,7 – 10 June). However, from June to July it increased by five percent (with 71,7 – 10 June until 75,33 – 8 July). For a strong epidemic course 2 times approached the mark 80 RUB/USD. (19.03.20 And 02.11.