It is quite common to find the Sales orders Total amount distributions such as Sub total (Line Total),Discount,Tax and Charges if any.
These distribution amounts will not be the straight database columns in the Order Management tables.
In order to find these need to explore the API.i.e.
OE_OE_TOTALS_SUMMARY.ORDER_TOTALS(
header_id In,
subtotal,out,
discount out,
charges out,
Tax out);
Total amunt of the Order=Subtotal+charges+Tax.
