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	$168.60	9.810%	$185.1397	$185.14	$185.15	$185.10
Purchase #2	$14.91	5.391%	$15.7138	$15.71	$15.70	$15.70
Purchase #3	$193.42	3.660%	$200.4992	$200.50	$200.50	$200.50
Purchase #4	$238.46	12.831%	$269.0568	$269.06	$269.05	$269.10
Purchase #5	$153.50	12.374%	$172.4941	$172.49	$172.50	$172.50
Purchase #6	$101.31	5.341%	$106.721	$106.72	$106.70	$106.70
Purchase #7	$138.26	10.484%	$152.7552	$152.76	$152.75	$152.80
7 purchase totals =	$1,008.46		$1,102.3798	$1,102.38	$1,102.35	$1,102.40