Hi Mojofr,
Adding a convenience fee ... are you referring to a "Surcharge" - in other words - you want your clients / customers to pay "the credit card processing fees" ?? Note, you can add additional charges to the cost of your item - i.e., Service Charges which can cover additional costs that you incur like shipping, taxes, etc. - not unusual per say however, if you price your items or services properly, you will recoup your costs. As for how you work with Visa - here's a link that should hopefully get you going.
If your thoughts are to simply have the client / customer pay your credit card processing fees in addition to your charges, you may want to consider how they will react - put yourself in that same position - how would you react ? Note: You may want to check with your States rules and regulations moving forward with applying Surcharges as each State has their own specific rules.
From a few years of personal experience - pricing your items and/or services is the key to happy customers and or clients. Your customers and or clients don't not care about your costs and they will be turned off if you nickle dime them for their purchases. Just some thoughts to consider of course.
jk
