No, it is not possible to skip rounds in long-term auctions. If you choose not to participate in one round, you cannot reenter the auction in the one after that. With one exception: if you did not participate in a round which results in an undersell of capacity (total capacity requested by bidders is smaller than total available capacity), the last large price step is cancelled, the auction proceeds in small price steps and you can participate again.
For further information, please check Ascending Clock Algorithm.