Penalties for handing work in late in classes

What do you think of penalties for handing work in late in classes?

 In my own opinion on this is , the 5% penalty is fair, but the percentage should have a limit of 15% overall. Students have much work to do in such little time. Most of the students give up on the class cause it's hard to get everything done at once, they ditch the class, and fail. Some are sick, or on vacation. I, Myself, is getting stressed over how much work I need to do this semester. The fact after a week of not handing in, you get a zero. That isn't fair to the students, most want to do well in the class, get caught up and pass.But they can't with so many zeros. Really, I think the 15% overall marks lost is very fair, and should be considered.