Council Tax Scam

As someone wholly innocent of financial matters, when I get my Council Tax Bill here's what I do: I divide the sum owed by 10 (the Council insists on being paid over ten months and although I could insist on paying over twelve months it's too much hassle). Anyway, I divide by 10. But if it comes to, say, so-many-pounds-and-so-many-pence, I just round it up to the nearest pound. Then I pay that each month. My assumption is that, if I am a couple of pounds in credit at the end of the year, that will be carried over to the next year. BUT IT ISN'T. At least not unless you phone up and go through the Kafkaesque system ("Press 1 for X, 2 for Y...etc.") designed to prevent contact with anything human. Imagine my surprise when, according to this years bill, my payments last year were penny perfect. That didn't seem right to me (given my careless ways with money), so I phoned up, went through the maze, and eventually discovered there was (so the council tell me and it is too much trouble to double check) the grand (and rather odd) sum of 38p (in credit) which had not been carried forward. Well 38p is neither here nor there, so it doesn't really matter. But, wait a minute, how many people pay council tax in Manchester? Now maybe they are all much better organised than I am, but I'm pretty sure plenty are just like me. How many don't notice that no balance has been carried forward, and just let it go? How many tens or hundreds of thousands of 38p's are that? A nice little earner. A bloody scam! Now this year I have a cunning plan. I will divide by ten and if it is so-many-pounds-and-so-many-pence I will round down rather than round up. That should leave me in debit at the end of the year. Let's see if that is carried forward, or if any red letters arrive demanding payment of said amount... I'm not thinking of taking bets on this.