I know this is kind of something you can google yourself (or probably have), but here's a couple SO links with some more info.

http://stackoverflow.com/questions/1458633/elegant-workaround-for-javascript-floating-point-number-problem

http://stackoverflow.com/questions/2876536/precise-financial-calculation-in-javascript-what-are-the-gotchas

http://floating-point-gui.de/languages/javascript/


FWIW, I typically use parseFloat, then toFixed(2) when trying to convert to currency format.  Of course this depends on the precision required though.

Example:  parseFloat("23432.234324").toFixed(2);  //"23432.23"