Add group discount functionality for POS

Hi everyone,

I have designed the POS with item line level discount (% or value) and now the client is asking to add group discount on the top of item level discount. That means group discount Amount should calculate based on Grand Total Amount.

I have the following database.structure.

Header Table:
SalesId       AutoIncrement
SalesDateTime   DateTime
SalesNo          VARCHAR
CustomerCode    VARCHAR
Total            FLOAT (holds before discount value)
Discount        FLOAT (Holds total line level discount sum value)
Tax                FLOAT   (Holds total line level tax sum value)
GrandTotal      (Total - Discount + TAX)
And other columns

Detail Table
--------------
TransactionId       AutoIncrement
SalesNo            VARCHAR (Linked up with Header Table)
ProductCode      VARCHAR
PRICE            FLOAT
QTY            FLOAT
TOTAL            FLOAT (QTY * PRICE)
DISCOUNT      FLOAT
DISCOUNTTYPE      VARCHAR
DISCOUNTVALUE      FLOAT      (CALCULATED BASED ON DISCOUNTTYPE)
TAX            FLOAT
TAXTYPE            VARCHAR
TAXVALUE      FLOAT      (CALCULATED BASED ON TAX TYPE)
LINETOTAL      FLOAT (CALCULATED BASED ON TOTAL - DISCOUNTVALUE + TAXVALUE)
AND OTHER COLUMNS

NOW I'M THINKING TO ADD ANOTHER TABLE CALLED 'SalesDiscountTax' (Pls suggest me better name for this name), to maintain the multiple taxes, and discounts.


NEW TABLE STRUCTURE
===================
SALESNO            VARCHAR
DISCOUNTTAXCODE      VARCHAR
RECORDTYPE      VARCHAR      (T / D / O)  - TAX / DISCOUNT / OTHER CHARGES
AMOUNT

Please suggest me is this the better way to maintain group discounts/taxes/other charges in seperate table. or you guys have better idea in mind based on your experience. PLEASE HELP ME.

Regards
YamihoStart Free Trial