Here is the sentence - My background reflects the ability to take multiple tasks to completion accurately and in a timely manner.

Question

My question, do I need a comma after completion?

Answer 1

It seems to me to be an awkwardly phrased sentence. This would be smoother:

My background reflects my ability to complete multiple tasks accurately and in a timely manner.

(No comma needed in either sentence.)

Answer 2

Further...! Even better phrasing would be this:

My background reflects my ability to complete multiple tasks accurately and quickly.

The phrasing "accurately and in a timely manner" is not good because it's not parallel; that is, you should have two adverbs or two prepositional phrases, not one of each.

http://grammar.ccc.commnet.edu/grammar/parallelism.htm