It sounds strange but it's true. I've 5 checks from CJ and don't know what to do with them. Each check is about $20 and I've to pay about this amount for clearing a US check here in Germany. I'd recommend to increase traffic and PR of your blog with the new free tool BlogRush.
Better question would be why you would set your minimum payment to be $20, and keep it for 5 months, knowing you have to pay for each check to clear.
You're right. I looked again at CJ and now you're able to increase the minimum payment. But in the past is wasn't possible. I no longer waste my time with CJ now.