In North America I see odds. On IASBet.com I see dollars and cents figures. What do these represent?

For example, if I see $2.30 does that mean odds of 2.3:1? This would imply I would be paid 3.30 on the win. Or is the figure the 'will pay' figure meaning I would get $2.30 for each $1.00 wagered?

Thanks,

-Duck