I agree with the above posters that you need to lower your shipping rates by lowering your actual costs.
Having said that, can I be the devil's advocate here and mention that if you print your postage through Paypal, you will not only get a pretty good discount on shipping, but you can choose to print the label without the actual cost showing on the label. hmmmm...Do with that information what you will.
I charge actual cost on shipping myself, with aoccasional handling charge of less than $1 if the item needs to be double boxed or if it's a large, oddly shaped item. I refund(through Paypal now) if the shipping that a buyer pays is significantly more than the actual cost- like more than pocket change. The calculator prevents overcharges most of the time.