Currently in Business Central, when having the Invoice Rounding check box selected in Sales & Receivables Setup, the Quantity field on the Sales Order Statistic page will show the quantity of items on the order lines plus one (if rounding is needed). I.e., the rounding line, even though not visible until the order is invoiced, still affects the Quantity on the Sales Order Statistics.

This can be quite misleading, making the sales statistics unreliable. Therefore, my suggestion is that the rounding line should be excluded when calculating the quantity.