You can specify that the Bitstamp exchange module purchase the full fiat amount entered into the machine, rather than just the amount of bitcoins dispensed to the user.
This example assumes the operator is using 4% as a commission. Adjust accordingly.
To do so, log into your server and run:
Below the line "var FUDGE_FACTOR = 1.1;" add:
var COMMISSION = 1.04;
Add variable to the 'amount' line as shown:
amount: satoshis * COMMISSION;
Press Ctrl-X, then Y, then Enter.
restart lamassu-server LAMASSU_ENV=debug
On a $5 transaction, you should now see $5 purchased on Bitstamp, instead of $4.82, for example.