It doesn't much matter if there are cuts or not. The fact is that no one has ever gotten infected with HIV via fingering - not once. Most people get infected by having unprotected, penetrative anal or vaginal sex. Don't do that, and you'll never have to worry about HIV.
HIV does not enter the blood stream via superficial cuts or scrapes (wounds that don't require medical attention). If you had a wound sufficient to allow HIV transmission, you would NOT be fingering anyone.