How much can I fudge resume dates?

Hey all,

So recently I was pushed out of my job due to a personal emergency issue that my employer would not accommodate for, and became increasingly hostile about. I chose to resign because I couldnt take it anymore, and felt they wanted me gone.

The issue is, I was there for only about 4 months. I want to stretch it to 6 because the skills and experience I gained from this job are highly valuable, but I know that come background check time, the lie will be obvious. I just wanted to ask if this is something I can still get away with, or would it be a mistake?