Android timer skipping numbers regularly

Question

I have an android countdown timer that is really inconsistent, and doesn't update the GUI regularly or correctly.

public boolean bTimerRunning = false;
public CountDownTimer timer;
private long currentTime = 180000;

public void onTimerTap(View v) {

    if (bTimerRunning) {
        //stop timer
        timer.cancel();
        bTimerRunning = false;

    } else {
        //start timer
        final TextView etTime = (TextView) findViewById(R.id.tvTimer);

        //initalize Timer
        timer = new CountDownTimer(currentTime, 1000) {
            int secondsLeft = 0;
            @Override
            public void onTick(long millisUntilFinished) {

                String currentTimeStr = String.format("%d:%02d",
                        TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished),
                        TimeUnit.MILLISECONDS.toSeconds(millisUntilFinished) -
                                TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished))
                );

                //save value to "pause" timer
                currentTime = millisUntilFinished;

                //show on text
                etTime.setText(currentTimeStr);
            }

            @Override
            public void onFinish() {
            }
        };

        timer.start();
        //set boolean
        bTimerRunning = true;
    }



  }

From what I have seen in the past SO questions, this is typical for the last few seconds of the timer, but I'm seeing it in the first few ticks, or just in the middle. How can I make my timer a better ticker? Would narrowing down the tick time work and rounding?