(non-)?greedy matching

me@box:~$ cat demo.txt

The price is $5.00 per unit, for a total of $50.

me@box:~$ cat demo.txt | grep -P ‘\$\d*\.\d*\b’

The price is $5.00 per unit, for a total of $50.

me@box:~$ cat demo.txt | grep -P ‘\$\d.*\b’

The price is $5.00 per unit, for a total of $50.

me@box:~$ cat demo.txt | grep -P ‘\$\d.*?\b’

The price is $5.00 per unit, for a total of $50.