Well, I think you are looking at the different rates based on the customer's location. I'm from Singapore and my rates are as follow: 3.9% + $0.50 SGD - Singapore 4.4% + $0.50 SGD - Overseas
The Fee use to be 3.4% for Worldwide customers and then they increased to 3.9% and now 4.4% Paypal is looking like a bank with ever increasing costs.
I think they should decrease the fixed cost for payments under 5 dollars to something more suitable such as 15 cents.
Fixed cost will not work because it'll be unfair to small transactions. Ultimately % is a fairer option, but maybe lower it!
That is why they use a % so the fee will be relative to the size. It's all about lowering the %, just like taxes!