Why not? Because money has a nominal value. One penny equals one. But one dime equals ten pennies. Definitely not the way to start counting!
Start math with the Sandpaper Numerals, Spindle Boxes, Red Rods, and Red and Blue Rods. They are all designed to give young children hands-on exposure to counting, quantities, and relative sizes of numbers.
Here is our Sandpaper Numerals reprint:
The Sandpaper Numerals are designed to be traced in the direction they are written. Your child uses his or her pointer and index fingers to lightly explore the configuration of each numeral.
You will see that the set includes 0 through 9 (as do the Spindle Boxes). The concept of ten and teens will be introduced in the next stage.
You can use cardstock, fine-grained sandpaper, and stencils to create DIY Sandpaper Numerals (or you can usually find a good used set online).
And here is a link to another DIY counting exercise:
When your child can count to 1,000 easily and understand the link between quantities and counting, start teaching about money.
Montessori for Everyone has a great exercise for this one at a very good price....it is called "Money Matching Cards"