For bare minimum, this is what I used to do for my games:
$40 to $100 Buy-in, 10 players with re-buys:
100 - .25
100 - 1.00
100 - 5.00
40 - 25.00
10 - 100.00
THis worked well for a while. Then the game grew so I went to:
100 - .25
140 - 1.00
120 - 5.00
40 - 25.00
20 - 100.00
Then I bought a custom set: The Music Shack:
200 - .10
200 - .25
200 - 1.00
200 - 5.00
100 - 20.00 (only because I had to buy Min 100, over size A-mold).
20 - 100.00 (these are Plaque's)
One thing I have learned, is that more larger denoms on the table help when cashing out. But some people like having lots of chips on the table.
I started to give (on one table of 10 players $100 buy-in cash game) 16 - .25, 16 - 1.00, 16 - 5.00, then for re-buys, I use the 20's I only use the hundos if its a crazy action night.