why is javascript rounding up the last 3 numbers code example

Example 1: rounding off numbers javascript

Math.round(3.14159 * 100) / 100  // 3.14

3.14159.toFixed(2);              // 3.14 returns a string
parseFloat(3.14159.toFixed(2));  // 3.14 returns a number

Example 2: rounding number to x decimals javascript

let num = 12.5452411;
num = num.toFixed(3); // 12.545