A fresh shit.
The Taxi! If you sounded 100, you should get 100.
If you have 100 on the counter, you have to get 100.

Teas are not included - they are given from above.
If the counter is 100, and you take 125 from a customer - then there is a high probability that the next customer instead of money will make you a swipe.

The change in the price of the service must be agreed with the customer before the provision of the service. Otherwise, they will send you. This is fraud in its pure form.

And on the question of pricing - swear a penny to the owner.