Black market it is then. You may not have noticed but there seems to be a coin shortage, so many stores require exact change of credit/debit card only. It is coming whether we like it or not. Christians have long awaited the "neither being able to buy or sell" part of Bible Prophesy to come about, up until this current generation it probably was not possible to institute but now computers make it possible.
Another thing that hurries this along is the more rapid self checkout in most stores and I read that Walmart will be switching to all self checkout soon.
Coin shortage ... probably engineered because people have been hoarding coins forever so nothing has changed.