I have Office XP PRofessional Excel 2002 SP3

I am trying to calculate sales tax in my spreadsheet and cannot come up with
the correct amount.

I48 = $660.17
A48 = 7.5%

G48 has =I48*(1-A48)

The result is $610.66

H48 is the sales tax result

=SUM(I48-G48)

The result is $49.51

I have a manual calculator that does sales tax and it does not match

$660.17
7.5%
$46.05 sales tax
Total minus sales tax is $614.12


Any ideas?

Thanks

Tom