Total normal and your reaction to it sounds pretty good. He's testing you. He's trying to see if the tantrum, the hitting, the pinching, the throwing of the toys, the dramatics, the whatever-it-is-that-will-force-you-to-give-in-to-him will work. Be consistent and let him know that these unsavory methods of behavior will not garner him any sort of attention, positive or negative. If you have to take him to time out 5 times in a row because he isn't getting the message, so be it. Just make sure that at the end of the time out you ask him "Why were you in time out?" and ask him for an apology and a hug, with a reminder that you don't want the behavior to continue along with suggestions as to what other, better options may be chosen.
Sometimes if my son starts throwing toys, I put the toy in time out on the mantle over the fireplace. When we initially started doing that, about 5 toys wound up on top of the mantle before he understood "Hmm. I guess if I keep throwing my toys, I'll have nothing with which to play." Now, it usually only takes one toy and he'll stop.
A good resource is Thomas Phelan's book 1-2-3 Magic. I like this method for several reasons: first of all, it does not involve yelling or getting over-emotional and secondly, the counting alerts your child to the fact that "hey, I'm doing something that I shouldn't be, and I'd better get my act together and make better choices before mom or dad get to 3 or there will be a time out or consequence for my continued disobedience."
Also try using verbal praise and recognition and 'catch him doing good'. If you are constantly having to resort to bribes and prizes (not saying that's what you're doing), then children learn that they don't have to do anything and can demand that there always be some sort of string/prize attached to it. Let him know that when he does a good job cleaning up his toys that you are VERY proud of him and give him a high-five or a hug. When you take a trip to the grocery store and he behaves and does not badger you for candy or toys, heap on the praise about what a good boy he was.
Good luck - he's testing you and how you react will set the stage for how he acts.