Breaker lets more Amps then its max
If a breaker is tripping regularly, that's a serious problem you should look at.   That is not normal or acceptable.  It means something is wrong with your overcurrent protection, or a defective device actually drawing too much current. 

It is normal for circuit breakers to allow overcurrent for a short amount of time.  This is needed by motors to start, incandescent bulbs to light, and many electronic power supplies to initially start up.  The term is called "inrush current".

Ultimately the purpose of breakers is to protect wiring and receptacles.  Overcurrent makes them excessively warm, but small overcurrent makes them warm slowly.  The breaker is designed to trip before this heat would endanger the wires.  

Many breakers also have an instantaneous trip, where they will trip immediately for very high current (i.e. a dead short).  This is many times the nameplate rating of the breaker.  

There is a chart for your breaker of how much overcurrent it will permit for how long.   Here is one example, there should be a vaguely similar chart for your breaker.   I'd get and see if it explains your breaker's tripping behavior.  If it doesn't, then either your measuring method is not precise enough, or you have a bad breaker.  I would be surprised at a breaker instantaneously tripping at 125% of rating.