how To count array?

I just playing with array with contain number for price and so on, no I want to count that array element. I meant, I want to know total sales. the array look like this if I encode that.
{“1″:33750,”2”:6000, “3”:80000}
the key will increase each time sales made. If the array look like that, how I count that friends? I want the value like this $a = 33750 + 6000 + 80000..and so on