VI-III-MCMXCVII
UNLESS YOU REALLY MEAN 31997 which would be XXX with bars over all three and then MCMXCVII
You could also write June.3rd.2006 as 06.03.2006 and the Roman numerals for these is... June.III.MMVI or VI.III.MMVI.
June-XI-MMVIII
June vii mmviii
06.05.2012
It is: VI-I-MMI
III/VI/MMI
VI-VIII-MMXII
It is: VI-XXVI-MMXI
It is: VI-II-MMX
It is: VI-XXIII-MMXI
VI-IV-MMXI
VI-V-MMXI