Many children have tics. Back in the old days they were called "nervous habits". Some outgrow them. Some don't. They are no big deal unless they annoy the child doing them.
You may want to get her tested for PANDAS or a strep infection which can cause tics.
If they really annoy us, we need to look within ourselves as to why. My husband used to do something that annoyed the heck out of me. I realized that what annoyed me the most was that I would tell him he did it and he would deny doing it. I would say, "LOOK! You're doing it again", but of course then he wasn't.
It was not until we realized that our little girl had tics, that I understood. It was funny - her vocal tics used to annoy the heck out of my husband. UNTIL we understood they were tics. No big deal, and not done because the child wanted to do it. That made the same tics as before no longer annoy my husband. That also caused my husband to understand he had some tics as well. The funny thing is that then what my husband did no longer annoyed me, either.
Stress may make the tics worse (both physical, and emotional... although during times of intense concentration, the tics may stop completely, only to come back with a vengeance as soon as the child relaxes). I figure that at least in the child's own home - let them tic to their heart's content. Home, at least, should be their one place of refuge - where they can totally relax. It is hard enough for them to not do it outside the home.
And yes... they can partially control them. At an effort... a cost to them. That doesn't mean it is not a tic. The main thing is... it isn't a big deal. Ignore it.
Is it normal? In a way... yes. In that it is not some pathological condition and often goes away on its own. How to make it stop? With maturity. My daughter's never stopped. Yes she has mild Tourette's. And no, she doesn't yell or blurt obcenities either - actually that is very RARE in Tourette's. It does mean she has some vocal tics, but they are no big deal and most people never even realized it. But a lot of my family members were never diagnosed but they do have tics.