It turns out IE is the only browser that needs the
viewBox to be set in order to scale an svg. I used a free program called inkscape to create my svg and it doesn't set the viewbox. Open the svg with a text editor and add this to the
viewBox="0 0 64 64"
Instead of 64, enter whatever the x and y of your bottom right corner should be for the size of the original svg. Not sure weather to blame IE10 or inkscape...
Update: You can update to inkscape 0.91 and the viewbox attribute will be added automatically.