Why is my code for the Cash Register algorithm subtracting wrong!

[brookalo12]

function checkCashRegister(price, cash, cid) {
  let y = [
  ["PENNY", 0.01],
  ["NICKEL", 0.05],
  ["DIME", 0.1],
  ["QUARTER", 0.25],
  ["ONE", 1],
  ["FIVE", 5],
  ["TEN", 10],
  ["TWENTY", 20.0],
  ["ONE HUNDRED", 100]
];
 let r = 0 ;

  let x = cash-price
  console.log(x,'x')
  let ct = cid[0][1]+cid[1][1]+cid[2][1] +cid[3][1]+cid[4][1]+cid[5][1]+cid[6][1]+cid[7][1]+cid[8][1];

  let change = [];     
for(let i = cid.length-1;i>=0;i--){
  let p = cid[i][1]/y[i][1];
    while((p > 0)&(x-y[i][1]>=0)){
       
       x = x-y[i][1]
       
        r += y[i][1]
        console.log(r,'r',i,'i',x)
       p--;
     } 
     change.push([y[i][0],r])
     r =0;
     console.log(change)
    }
 }

checkCashRegister(3.26, 100, [["PENNY", 1.01], ["NICKEL", 2.05], ["DIME", 3.1], ["QUARTER", 4.25], ["ONE", 90], ["FIVE", 55], ["TEN", 20], ["TWENTY", 60], ["ONE HUNDRED", 100]])

[JeremyLT]

You should not use any global variables that you mutate as the function executes.