Dividing dough into rolls
If you want to try to manage with the existing scale, it sounds like all you can do is try to measure larger quantities. For example, you could measure 1-pound or 2-pound pieces, then eyeball cutting them in half repeatedly until you get the 4oz pieces you want. When you eyeball things, it's often a good idea to try to get it into a uniform shape before you cut; we're a lot better at drawing a line down the middle of something symmetric than we are at cutting an irregular blob in half.

But a new scale would probably be pretty cheap and useful for other things, so it's not a bad idea if you aren't happy with the accuracy of what you have.