yes 0.30 is what you would enter here.
But i think it's very important for you to find out for sure if you are paying 30c per KWh, becuase this is the difference between profit and loss. Especially with scrypt/GPU mining. use a power meter at the wall to test how much the PC/s draw. Also if you are in the US you are almost certainly on 120v supply which is a little more inefficient then 240v systems. this is usually balanced out by the power cost in the US as it's usually cheaper then the EU. the best place is eastern Europe for mining. Low cost elec and 240v.
I don't like this calculator! even though it has many features it does not allow you to change the difficulty for future estimates.
http://www.alloscomp.com/bitcoin/calculator