drewshin, the librarian won't commit to a value (too risky). You are allowed to deduct the "fair market value". So if you are donating "Windows 95 Secrets", you'd be able to deduct about a buck.
If the books are about applications, and it's the current version, I'd claim 70% of the cover price as a deduction. If it's the next-to-most recent version, I'd use about 25% of the cover price. Older than that is where I use $1. If the books aren't about applications and they are still the current edition being sold, I'd go back to the 70% number.