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	$202.27	10.591%	$223.6924	$223.69	$223.70	$223.70
Purchase #2	$237.42	6.788%	$253.5361	$253.54	$253.55	$253.50
Purchase #3	$144.63	4.546%	$151.2049	$151.20	$151.20	$151.20
Purchase #4	$212.57	5.331%	$223.9021	$223.90	$223.90	$223.90
Purchase #5	$12.61	9.523%	$13.8109	$13.81	$13.80	$13.80
Purchase #6	$133.91	10.840%	$148.4258	$148.43	$148.45	$148.40
Purchase #7	$118.89	10.691%	$131.6005	$131.60	$131.60	$131.60
7 purchase totals =	$1,062.30		$1,146.1727	$1,146.17	$1,146.20	$1,146.10