To accept a payment a merchant enters the details in a VeriFone Vx510 or Vx570 terminal which then prints off a QR code. The customer then scans the code with their smartphone.

Alternatively customers can pay by giving the retailer a QR code holding Bitcoin value to scan or a private key to type out.

The system can also dispense the virtual currency, selling customers the coins using a printed QR code or private key, a stored value card or Bitcoin address.

Meanwhile, Bitcoin continues to see its value spiral downwards on exchanges. From a high of around $30 a coin in the summer it is now trading at less than $3, less than it costs to "mine" them.

You can read more about the POS system on the Bitcoin Wiki.