In order to find the answer to this problem, we want to do the following:
First, we need to find the sales tax value:
$34.78 + 6% sales tax
$34.78 * 1.06
$36.87 (rounded to the nearest hundredth)
The total bill is equal to $36.87
Now to find which bills to give to the server:
$20 + $10 + $5 + $1 = $36
Then, you can give the server 87 pennies.