I can't believe that my local newspaper did it again!
You use the present perfect tense to describe an action that began in the past and still continues, just as the kiddo in this article in our local paper, the Herald-Times, started singing in her choir years ago and still sings in that choir today.
To correctly form the present perfect, use the present tense of the verb "to have"--
She has. He has. It has.
You all have.
--combined with the past participle of the main verb. The past participle of "sing" is "sung," so the correct verb phrase is "has sung."