Experiment with something like this:

1) Create a rate table in a new worksheet (I'll assume Sheet2)

Col_A Col_B
Row_1 RateID Rate
Row_2 Rate1 17.5%
Row_3 Rate2 5.0%

Select A2:B3 range and name it:
InsertNameDefine
Names in workbook: LU_Rates
Refers to: (already selected)

Now, go to your invoice sheet.
I'll assume your total sales amount is in cell H9 and your rate amount goes
in cell H10.

Select F10
DataValidation
Allow: List
Source: =OFFSET(LU_Rates,0,0,,1)

G10: =IF(ISBLANK(G10),0,VLOOKUP(G10,LU_Rates,2,0))

H10: =H9*G10


Is that something you can work with?

***********
Regards,
Ron

XL2002, WinXP-Pro


"PJOS11" wrote:

HI I have just began to use Excel for invoices. I have set my Tax rate at
17.5%. but we use two tax rates here, the other is 5%.
How can I do this on one invoice.
Eg: 150+17.5%
150+5%