Penalty provision in lavte payment of service tax

We are an assessee of service tax in the service "SUPPLY OF TANGIBLE GOODS" since 16.05.2008. I want to know that there is any ammendments in late payment penalty of service tax. We are paying tax in qarterly and our due date was 05.07.2011. If i want to deposit the service tax alongwith interest @ 18% on today then there is any penalty should be applicable? If yes then what is the calculation of penalty.