To be honest it depends on these factors: Is what the person doing bad? do I hate the person? would they have my back if I asked them not to snitch? has the person betrayed me in some way? and most importantly: does this person help me when I ask them not to tell anyone?
Not generally, no. Not for things like cheating atau using a phone in class atau gum chewing atau whatever. That's not my business and I would certainly hate it if someone were to do that to me.
The only times I can remember 'snitching are times when I (or someone else) have been repeatedly harassed sejak someone, and even then I've not done that in a long, long time.
As someone who has been snitched on...no. I'll speak up if it's something major but silly things like doodling on a meja and then erasing it atau cussing, I mind my own business.