Roomate worries about a few extra bucks

I work with My roomate, he has clock out on the last min he can. I like clock out as early as I can. (we carpool)

I said does a few extra mins matter? Accoridng to his girlfriend when you are planing to get engaged, and have a wedding to plan every dollar counts.

But does a few extra mins really matter that much? At the end of the month it's only 15-20 bucks!