php mysql arrays and totals

I have been searching all over the internet and yet I have not found the answer to my problem. I have a mysql database which stores dollar amounts. The table is called items, the field is called amount. I use mysql_query("SELECT amount FROM items"); to get the amounts into the script. I would then like all the values to be added up for a grand total. I have tried this and the only thing I can come up with is a long string of numbers. instead of getting lets say 100, I would get: 10101010101010101010 any help would be greatly appreciated, thanks