Discounts appearing in AR Sales Order

Has anyone come across discounts appearing in AR Sales Orders that have not been put on via Web Tools.

I have what looks like a perfectly normal order in Web Tools with no discounts any where to be seen whether that be item, BP, coupon, expense etc etc, when this order synch'd to B1 a .03% discount appeared in the AR Sales Order and the order amounts were wrong in the footer.

When you delete the .03% discount all the figures tally correctly.

Any ideas?