I think that most users on the forum would not even consider using the camera to crop a photo. DPP comes with your camera, its a better tool for cropping. Many use Adobe Lightroom which will easily crop your image to a desired format such as 4 X6, or 5 X 7, for example. You can set custom sizes as well.
Some cameras allow you to set a different format size before you capture the image, and then the image is cropped to that size when opened in DPP (Canon editing software)
I also believe you can crop in the print menu, and the image will be cropped when you print directly from the camera. Not very useful unless you must print directly from the camera as part of your work flow.