Each time a merchant processes a credit card transaction, two immediate charges apply: the second is the transaction fee.
The transaction fee is a per-item fee that is added to every transaction a merchant runs through his or her account. Transaction fees can be as high as $.50 per transaction.
Note: For mail-order and internet transactions, there can be an additional transaction fee charged to the merchant by the merchant gateway solution provider
EXAMPLE:
You (the merchant) process a $100 sale.
Your transaction fee is $0.30.
$0.30 is deducted from the sale leaving $99.70.