Has nothing to do with tax dollars. Almost no one REALLY bases his decision on this topic in "tax dollars". It's usually just added as an after thought.
...the rest of that sentence... that's your reason to be against the death penalty. If you're sincere (and I believe you are), then stick with this because it's unassailable.
Personally , I don't have a problem with a death penalty myself...but it's a moral issue ...so there is no "definite" right or wrong answer...but it's the type of issue that a thinking man may constantly change his mind on.