HI Pierre Smits

I think formula should be:

percProfit = averageCost != 0 ? (profit / averageCost) * 100.00 : 0.00; and

totalPercProfit = totalCost != 0 ? (totalProfit / totalCost) * 100.00: 0.00;

I am saying this based on discussion given here: http://math.stackexchange.com/questions/105306/what-is-the-formula-to-calculate-profit-percentage

http://formulas.tutorvista.com/math/profit-formula.html

So formula given in your patch gives profit margin percentage and formula I am giving will give profit mark up percentage.

Different people have different opinion on this formula. So we can conclude this and then push community to commit the right solution.

This patch fixes the issue.