So is that for sure if im pushing a little over 156 watts
Nothing's for sure. What's your electric rate per kWh? That's the key to the increase in cost. Without it, no one can tell you how much the increase is.
The rest is 6th grade math that applies to everyone. Here is the forumula:
Wattage divided by 1000 X hrs on per day X 30 days per month X electric rate.
So 156 watts running 24 hours a day at a rate of $0.10/kWh will cost you:
156/1000*24*30*0.10 = 11.23 extra per month. (It would cost half this much when you change to 12/12.)
You can probably save this much per month by shutting off your computer when you don't use it, and changing the regular bulbs in the house to CFLs.