Your landlord is a fool! They should have raised the rent by that same amount and then offered you a $10 a month discount to pay it all at once.

Rookie doesn’t know how to play a numbers/scam game. /s

In truth, sorry you are only being given such a scummy “option”. The simple math shows that the more often you pay (i e. the earlier the recipient gets your money) the more they make in the long run. They should just do that and be decent about the whole thing.