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	$132.72	9.745%	$145.6536	$145.65	$145.65	$145.70
Purchase #2	$209.34	9.605%	$229.4471	$229.45	$229.45	$229.40
Purchase #3	$155.79	3.285%	$160.9077	$160.91	$160.90	$160.90
Purchase #4	$160.64	5.457%	$169.4061	$169.41	$169.40	$169.40
Purchase #5	$173.89	3.265%	$179.5675	$179.57	$179.55	$179.60
Purchase #6	$121.79	7.792%	$131.2799	$131.28	$131.30	$131.30
Purchase #7	$120.83	13.801%	$137.5057	$137.51	$137.50	$137.50
7 purchase totals =	$1,075.00		$1,153.7676	$1,153.78	$1,153.75	$1,153.80