Rather than using simple round numbers to determine the buckets you guys offer in your plans, you should set the bucket increments based on the amount of money it will increase your bill by going into the next bucket. For me, I'd rather see increments of $5. So rather than a bucket of minutes that goes from 500 to 1000 ($9), I'd like to know that if I go over my usual minutes that I'm only paying $5 more. This gets even more ridiculous around the $1000 minute mark. We estimate our usage (new user here) will be right around 1000 minutes. The difference in our monthly bill from crossing that mark will be $17! That's the difference between making Ting a great deal and just about the same price as other carriers.
So make your buckets for minutes (and texts, data) a certain amount of minutes for $5, $10, $15, etc. Sure, you can round the number of minutes to the nearest multiple of 10 or 100 or whatever. The point is, while the number of minutes that defines each bucket may be harder to remember, I will have the peace of mind of knowing that if I ever go beyond my normal usage amount that my bill will likely only go up $5.