Anywhere on their site??
If it is a fine print hidden somewhere, or in their terms and conditions or policy of 50 pages instead of boldly in front of you when you are paying, would that be a "hey! Its your fault. They told you"...?
They usually have it in FAQ section and not buried somewhere in TOS, written in small letters.
The only reason you wouldn't is to scam people in some shape or form and to some extent.
Doesn't make much sense to loose potential customer by stealing $7. Unless its a straight up scam mixer that is stealing everyone's money.