The majority of card transactions will not incur transaction charges but if you notice separate additional charges, please contact your card issuer or bank for more information as these charges were billed by them.
For example, if you used a debit card, you may be billed "transaction fees" for every charge you make depending on your bank's policy. Credit cards should not incur any additional transaction charge.
At our end, if your order was $9.99 (for example), only $9.99 will be deducted from your card and we will not (and can not technically) deduct any more than that. If you see a second charge of, say, US$0.30, that's your bank at work.
Please contact us if you believe that you were charged incorrectly.