Originally Posted by cordelli

Locally it's in bills for the change, not dollar coins or any other coins in the self service grocery store machines.

The train station and some other vending machines though are the opposite, they will dish out dollar coins.

One grocery chain, forget which one, limits you to just $8 in change, so it would not let you put in $15 in coin, only $8. Probably to keep the machine from getting full too quickly.