It's nice of you to give us your trust as easily, but I'm not certain that this optimism is shared by many other dominatrixes.
When I meet one of them, I'm used to give the tribute at the beginning because I want to reassure her about me and win her trust right away so that we both enjoy the session (I already heard stories about men deliberately leaving the session without paying), because I want us to get away from the monetary part as soon as possible, and because I myself don't trust my own memory : it already happened that one of her had to catch me when I was leaving after the session because I forgot to give her the tribute, which was extremely embarrassing.

In regards to the coins, it already happened to me that I prepare my session tribute the day before the session and found only 290€ in cash when it must have been 300€. Then I have been very tempted to have a look at the 20 cents, 50 cents and 1€ coins that I usually save to buy bread or coffee. There was enough coins to reach 10€, but I have nevertheless preferred to withdraw more bank notes at the ATM. (By doing so, I guess I probably robbed her of a good laugh.)
I have also already been tempted to complete a tribute with luncheon vouchers but I'm not sure she would have appreciated it.