I want to round a number to the nearest decimal place... if the number is 4.623, I want it to display 4.6 if the number is 2.36, I want it to display 2.7

Is there a function that does this? round(), ceil(), floor() don't do this and I've checked through all the math functions in my handy-dandy "PHP Functions" reference book. Thanks for your help!!! Or......if it's too hard to do that, I could just use a function that chops off the end of some decimals, like... if the number is 2.343234, I want just 2.3 or if the number is 2.545434534534534534, I want just 2.5 Thanks!!!!!!