but its always best if your domain matches your keyword.
From what I've seen I think google gives *a little* preference to wholeword.com vs whole-word.com then blah-whole-word.com just like they give a little prefernce to certain .tld's over other ones that are more likely to be informative or authoritative sources... but just a little
But so long as your keywords are in the domain/url it doesnt matter much in comparison to everything else.