Seller cancelled order, buyer wasn't issued full refund

[threestringbeantrees]

I, the seller, had to cancel an order.  Ebay handled the reimbursement but the buyer wasn't fully reimbursed.  They paid $18.22 for the order - $12 for item, $5.08 for shipping and $1.14 for tax.  The refund amount should be $18.22, right?  They received back $14.69 and I can't figure out how it came to be that figure.  Am I missing something? 

[rfmtm]

Was the buyer registered outside the USA, even though he may have had a USA address?