Short answer: No. But there is one reason you might want to.
Unlike trains, trams only travel inside metropolitan zones 1+2, and the fare across zones 1 & 2 is the same as the zone 1 fare.
Therefore, the cost for a tram ride is always the same. You don't need to touch off.
However, if you don't touch off at the end of your trip, your card's balance will not be updated until the next touch-on.
Myki cards don't update live
It's fair to assume that when you touch on or off, your online account gets updated immediately. However, that is not the case.
As far as we know, trams and buses don't have an active internet connection, until within the range of Wi‑Fi at terminals and other strategic points across their networks.
At that point, everyone's card data is synchronised with PTV's back-end servers, where a batch process is run on it, and balances are updated online. These batch processes are run at regular intervals throughout the day.
Touching off makes your online balance update faster
Upon completing its route, a tram synchronises its Myki card data with PTV's back-end servers. Your touch-off will thus be included in the next batch process, and your online balance will update.
In practice, an updated balance becomes available within 15-30 minutes after touching off.Last updated 21 Nov 2019