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	$158.62	9.756%	$174.095	$174.10	$174.10	$174.10
Purchase #2	$70.52	4.724%	$73.8514	$73.85	$73.85	$73.90
Purchase #3	$194.93	6.778%	$208.1424	$208.14	$208.15	$208.10
Purchase #4	$155.75	4.163%	$162.2339	$162.23	$162.25	$162.20
Purchase #5	$157.53	9.382%	$172.3095	$172.31	$172.30	$172.30
Purchase #6	$235.57	13.359%	$267.0398	$267.04	$267.05	$267.00
Purchase #7	$118.50	10.675%	$131.1499	$131.15	$131.15	$131.10
7 purchase totals =	$1,091.42		$1,188.8219	$1,188.82	$1,188.85	$1,188.70