Student or Learner
How do you pronounce : it tastes good. After "tast" only a "z" sound or an "ez" sound ? Or both possible ?
...Except that it is unvoiced - /s/. There may be some assimilation to the following /g/, but not much. So it's /teɪsts gʊd/ rather than /teɪst zgʊd/. (Of course, in informal speech. the whole consonant cluster may be reduced to /s/ and the /g/ may assimilate to the /s/, but that's not something that needs to be taught. But if you hear /m thæteɪskʊd/ don't be surprised.)
Bob is right, I don't know what the guy was thinking who wrote that /z/ is uttered.