Like EscortBiz said, everyone experiments with this when they first start a paysite, and the results rarely show an increase in sales. If the surfer likes your content he'll join whether it's a $1 trial or a $35 monthly signup, regardless of the cents afterwards.
Now one argument for the cent amount is masking it on the credit card bill so it doesn't look like an obvious porn membership
Ie. odd prices like 33.67.