Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

The Purpose of Change Machines 
I think you're talking about two types of machines, at least in the United States. The term change  machine usually refers to a machine that accepts large denominations of currency and returns an equal amount of currency in smaller bills or coins. Typically these machines are used to provide coins in exchange for paper currency, in which case they are also often known as bill changers. Exactly what bills or coins these machines return depends on the machine. Read the instructions on the machine to get the details (they're usually right on the machine). For example my apartment building has a machine that converts small bills like ones and fives to quarters, since the laundry machines only took quarters. The other type of machine are coin-cashing machines, like the Coinstar machines you might see at a grocery store. Many banks used to have these machines as well although in my area they're few and far between now. These machines perform the opposite function of the traditional change machine and convert smaller denominations (mostly coins) into bill form. For example if you dump all your accumulated pennies into the machine, it will probably give you bills and larger coins like quarters, dimes, nickels in exchange, after subtracting a small fee. I've heard that now, some of these machines may give you a gift card of some kind instead of bills, although they'll still subtract a fee from your original amount, usually. Once again just read the instructions and they should tell you. When my bank had one of these machines, they didn't charge a fee as long as you were a customer at the bank. I'm sure that varies from place to place and bank to bank though. Wikipedia's article has this to say (see the article for references): In some sections of the U.S., regional banks have begun offering free coin-counting services in the amount of a gift card. Refunds are often given in cash rather than in the form of a gift card. In some cases, it is not even necessary for the customer to have an account at the bank; the free service is offered as a way to attract new business from individuals who are not current account holders. TD Bank's "Penny Arcade" coin counters were free and available to both customers and non-customers in many branches, but as of November 2010, the bank charges a 6% fee for non-customers to use the machine.