function calculateTax(pWhich, lRate, lRateReverse, excObj, incObj, taxDisplay) {
    var lTempExc = stripAlphaChars(excObj.value);
    var lTempInc = stripAlphaChars(incObj.value);

    if (pWhich == 'inc'){
        if (lTempExc == ""){
            incObj.value = "0.00";
        }else{
            incObj.value = round_decimals(parseFloat(excObj.value) * parseFloat(lRate));
        }
    }
    
    if (pWhich == 'exc'){
        if (lTempInc == ""){
            excObj.value = "0.00";
        }else{
            excObj.value = round_decimals(parseFloat(incObj.value) - (parseFloat(incObj.value) * lRateReverse));
        }
    }

    if (taxDisplay != ''){
        taxDisplay.innerHTML = round_decimals(parseFloat(excObj.value) * (lRate - 1));
    }
}

function stripAlphaChars(pstrSource) { 
    var m_strOut = new String(pstrSource); 
    m_strOut = m_strOut.replace(/[^0-9.]/g, ''); 
    return m_strOut; 
}

function round_decimals(original_number) {
    var result1 = original_number * Math.pow(10, 2);
    var result2 = Math.round(result1);
    var result3 = result2 / Math.pow(10, 2);
    return pad_with_zeros(result3, 2)
}

function pad_with_zeros(rounded_value, decimal_places) {
    
    // Convert the number to a string
    var value_string = rounded_value.toString()
    
    // Locate the decimal point
    var decimal_location = value_string.indexOf(".")
    
    // Is there a decimal point?
    if (decimal_location == -1) {
        
        // If no, then all decimal places will be padded with 0s
        decimal_part_length = 0
        
        // If decimal_places is greater than zero, tack on a decimal point
        value_string += decimal_places > 0 ? "." : ""
    }
    else {
        
        // If yes, then only the extra decimal places will be padded with 0s
        decimal_part_length = value_string.length - decimal_location - 1
    }
    
    // Calculate the number of decimal places that need to be padded with 0s
    var pad_total = decimal_places - decimal_part_length
    
    if (pad_total > 0) {
        
        // Pad the string with 0s
        for (var counter = 1; counter <= pad_total; counter++) 
            value_string += "0"
    }
    return value_string
}