JavaScript - accounting

I'm posting this for someone that emailed me with a question... If anyone could help it'd be great!

"I am ... having some problems with a javascript assignment. I have to calculate a running total for an accounting page. After entering a quantity of any denomination the total should appear in the Total$ in till textbox. The denominations are pennies, nickels, dimes, quarters, etc... Any suggestions or advice would be greatly appreciated."

Thanks!