Master Gain Automation Interval Issue

Hi. When the hook happens in my song, I normally add like 2.5 db of gain, but for some reason, when I am adjusting the automation, I cannot get it to go to 2.5, it will jump around by about 1.5 db, and I can't set it to exactly what I want. I know that the trim feature will go up by 0.1 db intervals, but that adjusts all of the points. I just want to move one section of automation. Can anyone help?