It's fun to speculate about this (heck, I may even found a religion around it) but there's no way to prove that one is in a simulation.
It's possible that the creators of the simulation do not wish to let the cat out of the bag. Any test which aims to probe the limits of the simulation can, itself, be simulated at higher accuracy with only a slight loss of real-time speed. In fact, it's highly likely that different parts of the universe are simulated with varying amounts of precision.
Heck, even if the simulators goofed, they can always fix the simulation, rewind the universe back to a prior checkpoint, and begin anew.
It's possible that the creators of the simulation do not wish to let the cat out of the bag. Any test which aims to probe the limits of the simulation can, itself, be simulated at higher accuracy with only a slight loss of real-time speed. In fact, it's highly likely that different parts of the universe are simulated with varying amounts of precision.
Heck, even if the simulators goofed, they can always fix the simulation, rewind the universe back to a prior checkpoint, and begin anew.