Assuming they actually apply the money to the tramau centers, it'll take how many legally fired bullets to be fired to pay for the one they're complaining about?
This proposal has nothing to do with revenue or emergency rooms. Its purpose and motivation is exactly the same as that of the Nazi Nuremburg Laws...to oppress the target group. Jews in the case of the Nazis, gun owners in the case of Perata and his scum allies.
A professional armed robber or dope dealer might expend a box of rounds in a lifetime of crime, tax $2.50. A even the most casual shooter will expend 10,000 rounds in a lifetime, some people I know of shoot that many in a month. So criminals who actually cause the problem pay a couple of bucks and law abiding shooters pay $500 to thousands of dollars. What a terrific idea. If your purpose is to oppress gun owners.