Is it legal for a company to deny me "cashing in" my vacation hours when I resign?

I have been working for a company in Virginia for three years and have taken almost no vacation during that time, so I have two weeks of vacation time built up. I recently turned in my two week’s notice and was expecting to get paid for the vacation days I never used. Then I was told the “company policy” was that they didn’t do that. Is that legal?