Can I add a package as an additional to a rate code?

Hello

We are looking to charge for car parking at the hotel (£5 for 24 hours), however this is only for certain rate codes. Is there anyway I can add £5 to a rate code to post every night automatically. I have look at the billing on the rate code package and it seems to be 'Add rate separate line' or 'include in rate', but I don't want this £5 to go out to 3rd parties or anyone. I don't want it added to the rate. When the guest checks in on that rate code I simply want opera to post