How can I use toFixed method to array object values? [closed]

I have an array that consists of currency words and numbers. I need to round DIME and NICKEL values to 3.1 and 2.05 correspondingly

[
  [ ' ONE HUNDRED: $', 100 ],
  [ ' TWENTY: $', 60 ],
  [ ' TEN: $', 20 ],
  [ ' FIVE: $', 55 ],
  [ ' ONE: $', 90 ],
  [ ' QUARTER: $', 4.25 ],
  [ ' DIME: $', 3.1000000000000014 ],
  [ ' NICKEL: $', 2.0500000000000007 ],
  [ ' PENNY: $', 0.05 ] 
]

I tried to use toFixed and map methods, they didn’t work.

let my array = arr.map(e => e[1].toFixed(2)