Queue regulate all outbound

I know how to do this in a Cisco but in a Mikrotik alittle bit different. How can I setup a queue to queue anything incoming on the LAN side (multiple ports and subnets) that outbound to the internet what go over transfer speed? The reason being is we have 20Meg with 100Meg access port. Anything over 20Meg we begin to get charged per meg at a rate. I am trying to limit this so that everyone can’t burst over 20meg for total. We currently have seperate queue per customer but getting close to 20Megs.

“Meg” of what? MB or Mbit/s?