Hi,
Just thought I'd pass this along.... to send more than just the order total to Paypal so that customer can see details of the calculation here are the parameters.
 
amount variable goods_total
handling variable shipping_cost
tax variable tax_cost
discount_amount variable total_discount
 
I had a heck of a time figuring out the variable paypal uses to accept the discount figure....so I thought I'd pass it along.

TY... may come in handy...
Randy

Thanks so much!