myFormatCurrency.js

function myFormatCurrency(num, options) {
    // Defaults to showing cents with normal rounding on the cent. 
    // myFormatCurrency(1000.021) -> "$1,000.02"

    // options = 1    Don't show the cents 
    // myFormatCurrency(1000.021, 1) -> "$1,000"

    // options = 2    Show the cents with cent rounding up the next whole cent 
    // myFormatCurrency(1000.021, 2) -> "$1,000.03"

    if (typeof options  === 'undefined') { centsYN = 1; roundUpYN  = 0; }  // default to 0 if omitted
    if (options == 1){ centsYN = 0; roundUpYN  = 0; }
    if (options == 2){ centsYN = 1; roundUpYN  = 1; }
    if (options < 1 || options > 2){ centsYN = 1; roundUpYN  = 0; } // default settings

    if(isNaN(num))
        num = "0";
    var numOrig = num;
    sign = (num == (num = Math.abs(num)));
    num = Math.floor(num*100+0.50000000001);
    num = Math.floor(num/100).toString();

    var realcents = (numOrig % 1)
    var cents = realcents * 100;
        cents = Math.round10(cents, -2); // new addition to better handle JavaScript floating number handling

    var centsNormalRound = Math.round(cents);
    var centsRoundedUp = Math.ceil(cents);
    if (roundUpYN === 1){ cents = centsRoundedUp }
    else                { cents = centsNormalRound}
    if(cents<10){
        cents = "0" + cents; // make it two digits
    }

    for (var i = 0; i < Math.floor((num.length-(1+i))/3); i++)
        num = num.substring(0,num.length-(4*i+3))+','+num.substring(num.length-(4*i+3));
    if (centsYN==0){
        return (((sign)?'':'-') + '$' + num );
    }
    if (centsYN==1){
        return (((sign)?'':'-') + '$' + num + '.' + cents);
    }

    
    
}// end myFormatCurrency function

// https://stackoverflow.com/questions/42109818/reliable-js-rounding-numbers-with-tofixed2-of-a-3-decimal-number
// Closure
(function() {
/**
 * Decimal adjustment of a number.
 *
 * @param {String}  type  The type of adjustment.
 * @param {Number}  value The number.
 * @param {Integer} exp   The exponent (the 10 logarithm of the adjustment base).
 * @returns {Number} The adjusted value.
 */
function decimalAdjust(type, value, exp) {
    // If the exp is undefined or zero...
    if (typeof exp === 'undefined' || +exp === 0) {
    return Math[type](value);
    }
    value = +value;
    exp = +exp;
    // If the value is not a number or the exp is not an integer...
    if (isNaN(value) || !(typeof exp === 'number' && exp % 1 === 0)) {
    return NaN;
    }
    // Shift
    value = value.toString().split('e');
    value = Math[type](+(value[0] + 'e' + (value[1] ? (+value[1] - exp) : -exp)));
    // Shift back
    value = value.toString().split('e');
    return +(value[0] + 'e' + (value[1] ? (+value[1] + exp) : exp));
}

// Decimal round
if (!Math.round10) {
    Math.round10 = function(value, exp) {
    return decimalAdjust('round', value, exp);
    };
}
// Decimal floor
if (!Math.floor10) {
    Math.floor10 = function(value, exp) {
    return decimalAdjust('floor', value, exp);
    };
}
// Decimal ceil
if (!Math.ceil10) {
    Math.ceil10 = function(value, exp) {
    return decimalAdjust('ceil', value, exp);
    };
}
})();