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	$162.45	5.842%	$171.9403	$171.94	$171.95	$171.90
Purchase #2	$106.53	12.280%	$119.6119	$119.61	$119.60	$119.60
Purchase #3	$136.52	3.230%	$140.9296	$140.93	$140.95	$140.90
Purchase #4	$236.25	8.333%	$255.9367	$255.94	$255.95	$255.90
Purchase #5	$70.25	6.630%	$74.9076	$74.91	$74.90	$74.90
Purchase #6	$89.90	4.542%	$93.9833	$93.98	$94.00	$94.00
Purchase #7	$197.85	13.422%	$224.4054	$224.41	$224.40	$224.40
7 purchase totals =	$999.75		$1,081.7148	$1,081.72	$1,081.75	$1,081.60