Based on the search results, BNA transaction charges can refer to two different things:

1. BNA Convenience Fee: This is a fee charged by banks for cash deposit transactions done through Cash Deposit Machines (CDMs) for Domestic and NR, Savings and Salary Schemes, after banking hours (i.e. between 5:00 pm to 9:30 am) and on Bank Holidays. The fee is Rs. 50 per transaction for all Savings Schemes, except for Priority, Burgundy, Basic, and Small Savings schemes, which are excluded from the changes.

2. BNA Smart Payment: This is a payment processing service that uses a cost-plus pricing model to ensure fair and transparent rates for its customers. According to their website, there are no hidden or surprise fees.

It is important to note that BNA transaction charges may refer to other things as well, depending on the context.