Franz Enzenhofer created a webkitTransform plugin "the banana project for advanced HTML5 browsers" that helps you manage transforms and state:
"With jQuery.css you can't easily change webkitTransform CSS because webkitTransform isn't your average CSS. If in one step you add .css('-webkit-transform', "rotate(20deg)") and in next step .css('-webkit-transform', "scale(2.0)") the rotate value gets reset, as you've rewritten complete -webkit-transform CSS value.
Our goal with webkitTransform() was to fix this problem. With it, every element you assign webkit-transform css with can be edited in a simple way, without resetting every other -webkit-transform values."
More Info: Banana