It's not against the rules, per se, but there are certain policies that need to be met.

http://pages.ebay.com.au/help/policies/fundraising.html

I don't know if those policies apply when it's only part-proceeds that are being donated voluntarily (as opposed to fundraising specifically on behalf of the charity), but I would personally err on the side of caution and either seek written authorisation or not mention it in the listing. 

It is against the rules if you do not have written permission from the charity - the charity must also be a registered to conduct fundraisting activities. There are several other requirements for this type of listing.

The link to the ebay policy on this area is http://pages.ebay.com.au/help/policies/fundraising.html

DG you bet me to it by 22 seconds lol thats ninja power for ya

Thanks guys, I think it might be easier to make my good deeds secretly