Round tripping is most commonly seen in the lower anterior crowding situation. Similar to an airline ticket where you start in one city and then return, with Invisalign one is moving teeth away, lining them up, and then returning to the original spot (but rotated or some other improvement).
Most Invisalign providers can do this, but not all cases need it.
Round tripping is moving a tooth/teeth in a direction opposite to where it should go before moving it in the correct direction to align that tooth. Sometimes this is necessary to allow adjacent teeth to move to their positions or move teeth into a place to allow interproximal reduction.
Whether this occurs in your Invisalign treatment depends on your Invisalign provider and on the patient's occlusion.