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	$132.58	7.870%	$143.014	$143.01	$143.00	$143.00
Purchase #2	$54.70	12.588%	$61.5856	$61.59	$61.60	$61.60
Purchase #3	$222.71	8.182%	$240.9321	$240.93	$240.95	$240.90
Purchase #4	$237.55	6.743%	$253.568	$253.57	$253.55	$253.60
Purchase #5	$44.98	4.173%	$46.857	$46.86	$46.85	$46.90
Purchase #6	$246.53	11.712%	$275.4036	$275.40	$275.40	$275.40
Purchase #7	$243.51	8.681%	$264.6491	$264.65	$264.65	$264.60
7 purchase totals =	$1,182.56		$1,286.0094	$1,286.01	$1,286.00	$1,286.00