Speed of investments of Cashalot

[SOSFROMTHEDARKNESS]

I kept track of how many bars are filled every minute for the first investment, and I get that the speed of it isn't in whole seconds. I noticed this because its timer seemed off for two whole seconds (the two shouldn't show up at all but it does). Some of the other investments also have timers that seem to have an extra half second.

I believe that the actual speeds are 2.5, 3.5, 4.5, 5.5, 6.5, 7.5, 9, 10.5, 12.5.