It only appears in the charges window when you use "based on cart subtotal"... and I think you may need the "0" in front of the decimal, so it would be:
times: -0.3
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.