How to show floats with 2 numbers after the decimal point ?

In some situations, we can wish to show floating numbers with fixed number of numbers after the decimal point. In this case, ROUND(field, decimal places) can be used. Take a look on given samples:
SET @test = 4.5;
SELECT ROUND(@test, 2) AS testRound; -- should return 4.50

SET @test = 4.50;
SELECT ROUND(@test, 2) AS testRound; -- should return 4.50

SET @test = 4.23;
SELECT ROUND(@test, 2) AS testRound; -- should return 4.23

SET @test = 4.0;
SELECT ROUND(@test, 2) AS testRound; -- should return 4.00

SET @test = 4.01;
SELECT ROUND(@test, 2) AS testRound; -- should return 4.01