Need to shorten long integer

From 0.013234534 to 0.013

[twist]

I know this is simple enough, I know there is a function that does this but for the life of me I cant remember what it is. So instead of searching for the next hour if someone could give me a hand I would be very thankful.

[jatar_k]

echo round(0.013234534, 3);

[twist]

I knew it would be something simple, thanks.

[ams_david]

and also:

number_format(0.013234534, 3) = 0.013