It comes down, again, to the code requirements.
First, is the tent a 'detached structure?' Well, is it temporary? If this tent is going up for a one time event, it's clearly temporary. If it will be up all year, then it's not a 'tent,' it's a structure.
The second detail is: how many circuits? Will there be a panel at the tent itself? A single circuit (really two, as a multi-wire circuit counts as one) doesn't require a ground rod be driven ... more does.
Or, look at it as you would a job site. A 'spider box,' which often has eight separate 20 amp circuits coming from it, doesn't need a ground rod .... simply because it's temporary.
