I use composite door shims. The taper is much more gradual and they can be cut off with a knife.
Shimming is done at the back of the bowl,
Set the toilet down without wax, and see if it needs shims,
If so, place the shims now.
Lift the toilet, set the wax on the flange and drop the toilet back down.
After the toilet is snug to the floor, trim the shims.
A last touch would be to use polyseamseal from bolt to bolt around the front of the bowl. In Seattle, we're not allowed to caulk all the way around.
I find that clear works well with wood floors and tile.
If you're in Arizona land, then hj would caulk it 360.
Coins have never worked well for me.
Nor have the plastic shims.