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	$154.32	3.313%	$159.4326	$159.43	$159.45	$159.40
Purchase #2	$185.96	5.704%	$196.5672	$196.57	$196.55	$196.60
Purchase #3	$177.53	5.648%	$187.5569	$187.56	$187.55	$187.60
Purchase #4	$16.79	12.603%	$18.906	$18.91	$18.90	$18.90
Purchase #5	$233.79	13.445%	$265.2231	$265.22	$265.20	$265.20
Purchase #6	$151.72	7.819%	$163.583	$163.58	$163.60	$163.60
Purchase #7	$143.50	11.293%	$159.7055	$159.71	$159.70	$159.70
7 purchase totals =	$1,063.61		$1,150.9743	$1,150.98	$1,150.95	$1,151.00