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	$195.53	11.210%	$217.4489	$217.45	$217.45	$217.40
Purchase #2	$190.25	3.300%	$196.5283	$196.53	$196.55	$196.50
Purchase #3	$69.84	13.728%	$79.4276	$79.43	$79.45	$79.40
Purchase #4	$59.53	11.562%	$66.4129	$66.41	$66.40	$66.40
Purchase #5	$74.33	7.479%	$79.8891	$79.89	$79.90	$79.90
Purchase #6	$136.39	7.122%	$146.1037	$146.10	$146.10	$146.10
Purchase #7	$199.94	4.577%	$209.0913	$209.09	$209.10	$209.10
7 purchase totals =	$925.81		$994.9018	$994.90	$994.95	$994.80