Because sometimes `toFixed` rounds up:
```
>>> (1.974).toFixed(2)
"1.97"
>>> (1.974).toFixed(2).split('.')[1]
"97"

>>> (1.975).toFixed(2)
"1.98"
>>> (1.975).toFixed(2).split('.')[1]
"98"
```
In the last case, having 1.975 gp will show that you have 98 silver coins, not 97.

So I'm using Math.floor to round consistently:

```
>>> Math.floor((1.974 - Math.floor(1.974))*100)
97
>>> Math.floor((1.975 - Math.floor(1.975))*100)
97
```