I want to make literally everything in Illustrator to work with only one or two numbers in decimal place. Is that possible? I've tried googling but it looks like that everyone wants precision and not rounding. I want to do this because a lot of very thin lines are created between objects with like 0.012 pixels width and it makes a huge mess when moving objects.
I would like to mention that I mostly work with numbers when designing and whenever I want to create a new object, I input natural values; but this is not the same everytime and sometimes I move the shape or change sizes by hand.
Enabling "Snap To Pixel" is the closest solution. However, it doesn't change the properties of things made before that and you have to manually edit the properties of shapes; for example a box with 12.589px width will change like 13.589, 14.589, ...
Precision is often the same thing as rounding. But not allays. It is fairly typical that one would use a grid to accomplish this. Mind you pixel grid is not necessarily the one your looking for. But instead there is an option your looking for is view → snap to grid. Thing is, this grid is probably the wrong size by default you can edit it under Edit → Preferences → Guides and Grid... to set the size to whatever you want.
You can nolonger draw with any other rounding than that as long as snap to grid is on. So might be a good idea to lean to turn it on and off from a shortcut.
You can in newer verions of illustrator instruct the software to align to the pixel grid. This does not work for just the grid though. But i have wirtten a script for doing this you can find it here.