As my son says: The real problem with this question isn't the fuzzy math where you don't count the Bellhop's salary as part of the $27 they pay. The REAL problem is the manager giving back $5 because he decides they overcharged. They already paid the fucking money, that manager isn't giving any money back, let alone $5.00.
"Tradition" is just a word people use to make themselves feel better about being an asshole.