Can we just use in-game score without having anything timed? New to speed running so I'm not sure what people mean by RTA and IGT. Very sorry
As far as I know Cool Math Games is the only place to play HTML5 version, but you can play the Flash version on the web just fine which gives you a score at the end. If you are looking for an actual timer for your game you can install livesplit here https://livesplit.org/ to find your time with the end score you use the formula (60,000 - your score)1000. If you are looking for a built in timer for your game I don't believe this exists other than the small clock you can see in game. Also, if you haven't noticed there are two different version of the game - HTML5 and Flash. Cool math games is HTML5 and pretty much anywhere else is Flash.
There is now a Practice Mod for the Flash version of the game "60SBR_IGT", created by Sage (Zeekza). This allows you to replay and time individual Levels. You can find it as part of the Burger / Santa Run Collection