Maybe then?

=IF(OR(B2>SMALL($B$2:$B$25,5),AND(B2=SMALL($B$2:$B$25,5),COUNTIF($B$2:$B$25,SMALL($B$2:$B$25,5))>1,OR(COUNTIF($B$2:$B$25,SMALL($B$2:$B$25,5))<4,COUNTIF($B$2:$B$25,SMALL($B$2:$B$25,5))=5))),".",A2)