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	$214.95	7.733%	$231.5721	$231.57	$231.55	$231.60
Purchase #2	$183.36	11.193%	$203.8835	$203.88	$203.90	$203.90
Purchase #3	$78.70	13.848%	$89.5984	$89.60	$89.60	$89.60
Purchase #4	$26.28	8.788%	$28.5895	$28.59	$28.60	$28.60
Purchase #5	$71.82	10.589%	$79.425	$79.43	$79.45	$79.40
Purchase #6	$238.60	6.324%	$253.6891	$253.69	$253.70	$253.70
Purchase #7	$236.98	8.279%	$256.5996	$256.60	$256.60	$256.60
7 purchase totals =	$1,050.69		$1,143.3572	$1,143.36	$1,143.40	$1,143.40