I am aware of Revenue Ruling 78-38 (mentioned in the referenced link) and have used that for charitable contributions.
Keep in mind that revenue rulings are based on a specific set of facts, and the revenue ruling mentioned in the article was specific to charitable contributions. This was also the result of uproar over a prior revenue ruling.
Also keep in mind, that while some may use that ruling broadly, it does not guarantee that you will prevail if audited. It does however, give you a decent position if audited.
Your choice.
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
