The document discusses the inefficiency of metal currencies like pennies and nickels in the US economy. It costs more to produce a dollar's worth of pennies and nickels than their face value, while quarters and dimes are cheaper to produce. Hundreds of millions of coins are also taken out of circulation each year. Cash remains an important payment method for consumers of all ages, especially for transactions under $10. Younger consumers are more open to mobile payments. Retailers raise tens of millions annually through coin donation programs, showing consumers are willing to donate small change. Developing an API to convert fractional cash to donations or other payment methods could help address these inefficiencies.