Breaker sometimes trips when Microwave turned on
No a power strip will likely not help. If your electrical circuit is properly installed, undamaged and being properly used then it should not trip. Even just a $5 breaker being repeatedly reset could damage the panel, resulting in a $1000 repair. 

If you do get a power strip and it does trip before the electrical panel circuit breaker then it would likely be because the trip time-curve of the power strip is not designed to accommodate the power curve of the microwave, and you won't be fixing the problem, just delaying the inevitable, and possibly damaging the electronics of the microwave due to a disorganized power shutdown.

Residential "thermal-magnetic" breakers don't trip instantly at 20.1 amps. They are designed to trip under conditions that damage wiring, on an inverse time curve for thermal overload conditions, low overcurrents such as 1.5x the rating should trip between 90 and 300 seconds, 5x the rating should trip in 4 to 10 seconds, and a high magnetic inrush or short circuit of 10x or more they trip instantly. 



For instance if you have a 1200 watt power hungry coffee maker and a 1800 watt microwave (actual ratings of my appliances) on the same circuit then you have 3000 watts on a 2400 watt circuit. (Code requires kitchen circuits be 20A, 20A x 120V = 2400 watts.) That 125% overload should hold for at least 5 minutes, and if it never trips it would still be within NEMA specs.

Those numbers really create a situation that a microwave tripping a breaker means some real circuit evaluation is necessary. Your microwave is faulty and drawing enormous overloads, a circuit breaker is failing, you have a loose connection that could cause arcing that could start a fire, or your combination of loads is greatly overloading your wires and repeated resetting and resuming abuse will create expensive repairs.