The List
There are 67 5 letter words with X as the last letter. The highest scoring is XEROX at 19 points in Scrabble. 1 carry three or more vowels, which makes them useful for dumping a vowel-clogged rack.
ADDAXADMIXAFFIXANNEXBEAUXBEMIXBOLIXBORAXCALIXCALYXCAPEXCAREXCHOUXCIMEXCODEXCOMIXCULEXCYLIXDESEXDETOXDEWAXEMBOXENFIXFEDEXFOREXGALAXHAPAXHELIXHYRAXIMMIXINBOXINDEXINFIXKYLIXLATEXLIMAXLINUXLUREXMALAXMIREXMUREXPANAXPHLOXPODEXPYREXRADIXREDOXREDUXREFIXRELAXREMEXREMIXRETAXREWAXSALIXSILEXSOREXTELEXUNBOXUNFIXUNMIXUNSEXUNTAXVARIXVIBEXVITEXXEROX