I'm a charter bus driver who had an accident. My employer is asking me to pay for part of the damage to the bus

I was turning my bus around after dropping off passengers at the Sun bank arena in Trenton, NJ. for the Disney on Ice show. I backed in near a dumpster and when I pulled forward the tail swing off the bus caught the left rear side and shattered a side window and scraped the side of the bus. The company wants me to pay $750.00 to an invoice they made stating it's half the expense of the window. The employees hand book mentions nothing of having to pay for damages to equipment as part of your condition of employment. Is it legal for them to ask me to even pay for damages that should be insured.