Hi Elmer,
I suggest you to explore before options in customizing, so, I agree with Robert. Think that you can create new conditions and with the help of VOFM formulas (according this z table) solve the values.
In the other hand, think also in determine the conditions using this customer values. You can add customer fields for pricing . Please, see SAP Note 531835 - Using field PSTYV in the condition access for further information.
I believe you can do it with enhancements.See Note 301077 - User exits for the interface to accounting, perhaps with EXIT_SAPLV60B_008, splitting one line in 2 or more lines. You can see a sample (but for other requirements) where you have some coding for include ZXVVFU08 in Note 611040 - Down payment invoice for Italy where you can see how to add items in the FI doc (command APPEND xaccit). But if you try this, please, be careful and think in this tool or technique as the last resort.
I hope this helps you
Regards
Eduardo
