YEs, the machines take quarters. I always put my S&S card in, create a account (sort of) and keep it in until I am done playing that machine. You accumulate points towards a freel $10 of playing money. The last cruise I think they ended up giving me $60 or so bucks, which I gave back...
2007 Victory & Triumph
2008 Conquest & Liberty
2009 Valor, Freedom, and Splendor
2010 Glory and Liberty
There are quarter and penny machines as well as dollar, five dollar and two dollar machines.
I would suggest cashing in your quarters at the bank before you sail and tucking those bills back for gambling. You can then buy rolls of quarters on the ship. Why carry around the weight of those quarters with you?
Been there - done that:
2005 Holiday, Sensation, Conquest,
2006 Conquest, Celebration, Holiday,
2007 Freedom Grand Med, Holiday
2008 Fantasy & Sensation,
2009 Fantasy, Holiday & Dream Grand Med
2010 Fantasy and B2B Elation
2011 Monarch of the Seas
2012 Booked - Breeze from Barcelona 12 days