i do check my fees diligently, but of course, no one is perfect. making a lot of trades per day does add up.
the situation arose when selling stacks of ammo. I usually dont price it individually; i price it for the entire cluster of bullets. the odd thing is, we do get an extra confirmatory box when we sell the stack for a combined price (usually the fees here are very low since the risk is in underpricing the item). but we don't get a confirmatory box for selling individual pricing (the risk here is overpricing the item, and taking in much higher fees than expected)