I would recommend that you save everything (including rollsCount using the basic datastore, then save the RollsCount to an ordered data store, when the player leaves. (Don’t remove the RollsCount from the basic datastore). This should let you have the data in an ordered datastore for leaderboards.
Depending on the player count, you may also be able to make use of the ListKeys function to loop through every single save, and add the RollsCount to an ordered data store. However, this only works on smaller scales (if you want more info on this, lmk)