Create a refund

$ curl -X 'POST' 'https://services.taxamo.com/api/v2/transactions/T60YAAAABteWsHwfho8xUz1l4fuo/refunds?line_key=SQ0Kuuvp4P9VnEzq&private_token=priv_***********&total_amount=100'

{
    "total_amount": 100,
    "tax_amount":   16.67
}