Hi. I wrote something like this. I set the timer to increment the counter variable every 0.1s. Button A pauses / resumes timer operation. Button B resets the counter (the counter variable). The current counter value is displayed in the main loop of the program, scaled to seconds and hundredths of a second. One value of the counter variable in my case corresponds to 0.1s. You may need to modify the display_time function, because in my case (firmware 1.4.5) the lcd print function displays the result in the previous place overwriting the previous result. In later firmware the displayed result may overlap the previous one.
This is also an incomplete example, so the displayed time may overwrite hundredths of a second after exceeding 99 seconds