Discount coupon tax calculation problem



Sub-Total: $14,390.00CAD

Priority Ontario Rate (1 x 243.00lbs) (Best Way): $200

product tax: $1,896.70CAD

Total: $16,486.70CAD

Subtotal + shipping rate( Ontario) = $14590

$14590*13(tax)/100 = $1897


I Want to charge Tax on just a Total and want to exclude the shipping