You just need larger face value coins ($2 and 5$) and phase out the small ones. Inflation always devalues coins and most countries simply issue higher value coins. It always amazes me the US has a 1$ note; but I guess it comes with the tipping culture and low wages. Breaking currency into $ and cents is something that was never going to age well also (eventually cents are worth nothing unless you revalue the $ every 50 years). I think currencies like the Yen which have a single unit are more practical.