I've owned numerous carbon frames, forks and seatposts. Never owned a torque wrench that can register as low as 5Nm and never had a problem with a bolt loosening when I was riding and never broke a bolt or carbon part.

If you're clueless, buy a torque wrench to learn with, but keep in mind that loosening a bolt tightened to 5Nm require moe than 5Nm of torque. If you tighten a bolt by hand and then apply a torque wrench to it, it will require a bit more torque to get the bolt turning again.

My point is to not rely on a torque wrench for tightening M5 bolts on a bike.