Rent is always just a little short

[Allen Clark]

I am renting to three room mates and charging $3,500/month. They are 21 so young and a bit inexperienced. They're good kids though and have been good tenants. The pay the rent individually to me via Venmo which is convenient for all. Each month they are just a bit short on the rent. This month they were $0.33 short when all three portions were received. Now I don't really care about $0.33 and they are good tenants so whatever but it does bug me a little (so maybe i do care??). 

Should I pursue the $0.33 so they know that rent is due in full each month? I'm likely just to let it go.,.