This tool allows you to rotate a layer around a pivot point using a slider or entering a specific value for degrees. All children of the selected layer will rotate, too.

Select the layer you want to rotate. 

Select the pivot point for rotation. This point will remain stationary as the rest of the layer rotates.

Use the slider to rotate the layer on the canvas. To be more precise, you can enter a value in the Degrees box. Focus out of the box to see the results before saving.