Arizona authorities this week charged suspected members of a criminal ring thought responsible for 10 percent of all fake money in the state after some members sent a printer, jammed with counterfeit bills, out for repair.

A three-month investigation by the U.S. Secret Service and the local sheriff's office nabbed 10 suspects for crimes including forgery, weapons violations and drug charges, according to the Southwest Valley Republic. The ring of counterfeiters allegedly included two Wal-Mart cashiers who accepted the fake bills as payment for big-ticket items in order to put the faux money into circulation. The suspects would then go to a different Wal-Mart and return the items for cash, according to the news report.

The counterfeiters manufactured more than $160,000, according to officials, most of which ended up in circulation.

Many software companies and printer makers add software to their products to make copying or printing currency nearly impossible. Adobe Systems has quietly added technology to its graphics software to prevent consumers from copying and manipulating images of the world's currency. Hewlett-Packard also ships anti-counterfeiting measures in its printers, according to privacy expert Richard Smith.