How To: Give Discount for Choosing Certain Payment

I'm wishing to give a percentage discount for users who choose a certain payment method over another. For example, they choose to pay with Google Checkout instead of PayPal. How might I go about this? I have HikaShop Business.

Thanks!

I see that I can apply a -% in the Google Checkout payment plugin. Any way to do it with Discounts? Currently, using a -% in the payment plugin, it shows:

Payment fee -$xxx.xx

I don't like to to see the words Payment fee.

You can't use discounts for that and payment fees are the way to go.

As for any text in HikaShop, you can change that text via a translation override:
www.hikashop.com/en/download/languages.html#modify

Ok, thanks Nicolas. I can make it work.