Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$165.58	4.852%	$173.6139	$173.61	$173.60	$173.60
Purchase #2	$13.31	3.349%	$13.7558	$13.76	$13.75	$13.80
Purchase #3	$75.57	3.452%	$78.1787	$78.18	$78.20	$78.20
Purchase #4	$149.31	13.150%	$168.9443	$168.94	$168.95	$168.90
Purchase #5	$80.84	8.223%	$87.4875	$87.49	$87.50	$87.50
Purchase #6	$204.56	13.697%	$232.5786	$232.58	$232.60	$232.60
Purchase #7	$218.40	13.761%	$248.454	$248.45	$248.45	$248.50
7 purchase totals =	$907.57		$1,003.0128	$1,003.01	$1,003.05	$1,003.10