Lau was the only one who knew where the money was, and the Joker only found out about it after he broke out of MCU with Lau. Joker said Lau was a squealer and he got him to spill the location of the cash after he busted him out of "Gordon's cage" and escaped in the cop car. So obviously, Joker never went there. There's clearly no concrete answer, which I think makes it that much more mysterious and intriguing. The Joker in the film had the power of a hurricane, ripping right through Gotham, yet the evasiveness of smoke, which no matter how hard you try, can simply not be caught. Adds a lot to character in my opinion. Even his "buzzing" theme, which kicks off the bank robbery, leaves as it quick as it comes, almost like a calm before the storm, representing the upcoming and uncompromising chaos caused by the Joker.