AWS Elemental MediaConvert CBR - Is there a way to output a hard Constant Bit Rate?

I am using presets with MediaConvert. When I set up a preset to use CBR video bit rates, I am seeing output bit rates all over the board and not capping or staying steady at the set CBR rate. Ideally, is there a way to have it use a "hard" CBR rate? Alternately, is there a way to set a top bit rate and not have it go over that rate? So if I need video at 5mb/s, I get a max overhead of normal 10%? Right now, I see video bit rates at sometimes up to 60% higher than the set CBR, and it is going over the network limit on the streaming video I am trying to do. If I wanted VBR, I would have it set as such.