What may be interesting only to me, is that the mathematical definition of lowest common denominator involves a discussion of "vulgar" fractions (fractions with whole numbers in the numerator and denominator) and of those fractions, there are proper and improper fractions.
Certainly in the world of southern manners, one would be offended to find out that there is such a thing as a proper vulgar fraction. Most proper southern folks would consider anything vulgar to always be improper. Mathematics doesn't always comply with manners!
For example, 2/3 is a proper vulgar fraction.
It would seem that the LCD is always a prime number by intuition when we are talking about vulgar fractions, but I don't remember enough from early life to provide any proof (that doesn't seem it would be needed, anyway, if a LCD is composed of primes, then it should be an LCD, right, the smallest of the primes should become the LCD).
So, Ray, the answer to your question would be that if we're talking in vulgarities, the answer to your question would depend on whether we were discussion prices in dollars or cents.