Ahah when I first saw that title I thought it read "Mouth to Mouth"
Keep in mind that insurance is calculated for the year, with the summer months paying a higher percentage of the costs. WHen they do month to month, they split it up over the year to make it even. Which means that if you start in May and cancel in October, you'd actually have to pay them the remainder of what's due since they'd assume you'd be paying it evenly.
Those who know more than me, correct me if I'm wrong.