How do you get the rotation value of an svg object with snap.svg?

Question

So, I'm using snap.svg and I'd like to dynamically rotate an object over time. Something like this:

function rotateObject()
{
    myObject.rotation += value;
}

The problem is I don't know how to access the rotation values for my display objects (or if they even exist!) So given something simple, let's say a circle declared like this:

snap = Snap(800,600);   
circle = snap.circle(400,300,50);

I know I can access the x and y values like so:

circle.attr("cx");
circle.attr("cy");

What I need help with is:

1. Is there a rotation property of some sort that I can use to rotate this object?
2. If not, how do I rotate an object with snap.svg?

Answer 1

Better rotate objects using Snap.Matrix()

The way suggested by Ian, works for me perfectly while I used Chrome version < 36.0 When I updated Chrome to 36.0.1985.125 I saw bug with text rotation.

So, the soulution was using

var matrix = new Snap.Matrix();
matrix.rotate(-90, x, y);    
Paper.text(x, y, 'Text').attr({
                    fontWeight: 'bold',
                    fill: '#434343',
                    transform: matrix
                });

instead of

Paper.text(x, y, 'Text').attr({
                    fontWeight: 'bold',
                    fill: '#434343',
                    transform: 'r-90'
                });

Maybe it will be useful for somebody.