Some children want to negotiate everything! Parents just don't have time to negotiate everything, nor should they. Children should have some things that are negotiable, like where they want to do their homework, what to have for dinner, or what pajamas they wear to bed. They should also have some things that are not negotiable, like doing their homework, wearing their seat belt, or going to bed at a certain time.
It is helpful for the parent to say at the beginning of the communication, "This is negotiable, or this is not negotiable". In this way, the child knows ahead of time which one it is, and as a result this phrase will cut down your arguing dramatically. This will be especially true if you "stick to your guns" when you say "this is not negotiable".
For more on negotiation watch my short video: