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	$182.53	7.652%	$196.4972	$196.50	$196.50	$196.50
Purchase #2	$151.43	7.426%	$162.6752	$162.68	$162.70	$162.70
Purchase #3	$233.40	9.870%	$256.4366	$256.44	$256.45	$256.40
Purchase #4	$189.62	10.463%	$209.4599	$209.46	$209.45	$209.50
Purchase #5	$161.66	6.626%	$172.3716	$172.37	$172.35	$172.40
Purchase #6	$45.58	13.363%	$51.6709	$51.67	$51.65	$51.70
Purchase #7	$140.97	13.448%	$159.9276	$159.93	$159.95	$159.90
7 purchase totals =	$1,105.19		$1,209.0390	$1,209.05	$1,209.05	$1,209.10