"This dismissal without prejudice would neither terminate the litigation in state court nor necessarily bar the action and claim for refunds under the statute of limitations.[??17] Finally, assuming for purposes of argument that the January 12 memorandum opinion and order was a final judgment, compliance with N.D.R.Civ.P. 54(b) would be required because unadjudicated claims for refunds and for clas" . . . . .