How to stop rendering early

I have a question for I Render. We are rendering at work and set it up for 10 passes. The quality that we need was good at two passes. Is there a way to stop the render and save the progress that we have?
 

SIngle click on the red render icon on the toolbar in the rendering window once. It will stop the rendering after it completes the current pass.

Double clicking on that button will stop the rendering immediately, in the middle of a pass, so you don't want to do that unless you are going to restart the rendering again.

You can also set the number of passes to 2 on the Options/Render tab before you start the rendering.