Each seller's commission, calculated the moment the booking is saved

On whichever you choose, rule by rule. On the Profit base it is calculated on the difference between what the passenger is charged and what the operator is paid, with the agency fee included. On the Total-charged base it is calculated on everything charged to the passenger, with no costs deducted. You can have one seller earning on profit and another on sales, in the same agency.

Graduated. Each rate applies only to the portion of volume that falls in its band, not to the whole. With 5% up to ten thousand and 8% beyond, someone who accumulated fifteen thousand earns 5% on the first ten thousand and 8% on the remaining five, not 8% on everything. That way crossing a tier never produces an artificial jump. Volume accumulates per currency, without conversion.

The amounts earned, no. Each seller only sees what they earned themselves, and that restriction is enforced in the database, not merely hidden on screen. On the agency dashboard they see their own commission and their rank, but not their colleagues' amounts. The full leaderboard with names and figures is for Administrator and Supervisor.

No. It calculates the amount and records it on each booking, together with the base and rate that were used, but there is no settled or paid status, no payment date, no receipt and no Excel or PDF export of a monthly settlement. Payment happens outside the system. What Tripwise solves is that the number is correct and nobody has to rebuild it in a spreadsheet.

No. The commission is frozen when the booking is saved, with the base and rate in force at that moment, and stored as part of that booking. Changing the rule affects whatever is saved from then on. If you want an earlier booking to pick up the new rule, it has to be saved again.