Hi. This suggestion is something that can be made by code, but for us who doesn't know how to fuzz with code this could be a good thing to add as a standard feature.
Basically what this could be is that if you have say a 200$ donation goal you can have it in increments of 10$ and have it say 1/20 in the bar. So if someone donate 5$ and it will go half way up. If they donate 10$ it will go up to 10 and finish the first bar. Someone donates 15$ it will go up, fill the first bar and then go half way up the next one.
I know with code you can also have so bits count in on this and count cents and dollars as they come in. But for a starter just having increments on general donations might be a good addon