Select random number by specific number

How to get random number [10,20,30,50] in MySQL. i have try using ROUND(RAND() * (50-10) + 10) but, this will generate number 11,12,24, which i don't want. I wonder this code will like this FLOOR((RAND([5,10,15,20,25,30,35,40])). but how? thanks in advance..