according to the dictionary it can be pronounced both as Dey-tuh, Dat-uh, or Dah-tuh.
So using your phonetic spellings - neither because that would mean I'm saying ta at the end as in ta-ta; not tuh (rhymes with duh)
I love how many grammar fascists we've got here that apparently don't know how to spell phonetically.
I hope this isn't a precursor to 1000 tah-mey-to v. tah-mah-to threads.