If you change your account to PayPal micropayments, you pay less in fees for purchase below $8, but pay more in fees for anything above that: https://micropayments.paypal-labs.com/
With that, the fee is $0.05 + 5%
Without that, the fee is $0.30 + 2.9%
Without it, if someone sends you $0.40, you receive $0.09 and PayPal gets $0.31.
With it, if someone sends you $100, you get $94.95.
The cost of doing business with PayPal is much higher though, trading or selling virtual currencies is against their policies, and will likely get your account balance locked at some point. Fraudsters will buy your bitcoins with stolen cards or charge you back. I would not go there.