I have seen one scenario where engineers get sales commissions: quants in investment banks. Typically in banks traders will get 3% of PnL before costs are stripped out, or 10% after costs. Traditional sector coverage sales will get a volume based commission. This always leads to tension between sales and trading as one is compensated on volume and the other on margin. Etrading sales get sales credits on channel volume, not sector volume, which is often another source of tension. And finally, the quants coding up new pricing models may get sales credits on trades priced with those models. No doubt there are some interesting comp models at automated or systematic trading hedge funds where there's no real distinction between traders and coders, but I have no first hand experience there.