Auto Sum calcs not right

Hi all

This one has been doing my head in all day

I have made a programme to calculate the VAT, but the auto sum is calculating about 5 decimal places instead of just the 2 that shows on the screen so the total sum at the end comes up short

Formulas that are in the cells

A1= £2.89 (price without VAT manually entered)
B1 = A1/100*17.5
C1= A1+B1
this shows on the screen as
A1= £2.89
B1= £0.51
C1= £3.40
which is correct

but if I auto sum 2 rows on the exact same amounts of £3.40 then insted of the total price showing as £6.80 it shows as £6.79

when I format the cells to general instead of currency this is what shows on the screen
A1= 2.89
B1= 0.50575
C1= 3.39575

which is also right and when you x 3.39575 by 2 it = 6.7915

So even when the cells are set to the currency format it looks like the auto sum is still working in the general format (with 4 to 5 decimal points) instead of the currency format (with 2 decimal points) hence why 1p short

Does anyone know how I can get round this problem or how I can set the atuo sum to only calculate 2 decimal places insted of 4 or more

I am using windows 7 with Office 2010 if this makes a difference

Any help on this would be greatly appreciated

thanks

Gordon

Thank You very very very much

put in both and worked a treat

Very much appreciated

Thank you