Mmh, could you "show me your work"? Because I don't see how you end up with these numbers.

2.9% of $1 is $0.029

$1 + $0.029 + $0.35 ~= $1.38

95% of $1.38 is $1.311

Clearly that doesn't make sense.

Or does it mean that Patreon gets 5% from the creator's share and then 2.9% + .35 cents on your side? So if I want to pledge $1 then I have to pay $1.38 and the creator really only receives $.95? If so that seems misleading. Also in this case it would mean that in that case Patreon ends up taking 31% of the actual money spent by the pledger.