Thats private currency just like the Federal Reserve currency its unconstitutional. To be legal it has to be government currency and to be completely constitutional it has to be physical gold or silver, not fiat currency. But we got suckered in 1913. president Wilson got bought off and then later agreed it was the biggest mistake he ever made. And the truth is even in a capitalist society we don't need currency, barter works fine. And it can be used to avoid taxes which works out pretty well for companies.
I would prefer that we just leave the land of greed and move on to a more fair and equitable system of wealth distribution. Repubs like to think that, thats what government programs are doing, redistributing wealth to the poorest. But in fact if you just look at the numbers the exact opposite is true. With capitalism
wealth will naturally occur to the top 1% which is what we're seeing now. Its the only the level of society that is seeing an increase of wealth.