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	$198.79	7.211%	$213.1247	$213.12	$213.10	$213.10
Purchase #2	$210.62	5.599%	$222.4126	$222.41	$222.40	$222.40
Purchase #3	$44.95	7.131%	$48.1554	$48.16	$48.15	$48.20
Purchase #4	$56.36	12.839%	$63.5961	$63.60	$63.60	$63.60
Purchase #5	$160.32	6.763%	$171.1624	$171.16	$171.15	$171.20
Purchase #6	$236.93	7.800%	$255.4105	$255.41	$255.40	$255.40
Purchase #7	$67.50	13.433%	$76.5673	$76.57	$76.55	$76.60
7 purchase totals =	$975.47		$1,050.4290	$1,050.43	$1,050.35	$1,050.50