The problem with that monetary system is not that it wsn't base ten; it's that it wasn't base anything consistent.

Four farthings to the penny.
Twelve pence to the shilling.
Twenty shillings to the pound.

Before laughing too much at the mote that used to be in someone else's eye, we should consider the some of the logs in our own, e.g.

3 teaspoons in a tablespoon
2 tablespoons in an ounce
8 ounces in a cup
2 cups in a pint
2 pints in a quart
4 quarts in a gallon

What's 17.5% of 3 quarts, 1 pint, 1 cup, 3 tbl, 2 tsp? Please answer in drams.