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	$98.72	5.764%	$104.4102	$104.41	$104.40	$104.40
Purchase #2	$150.67	7.860%	$162.5127	$162.51	$162.50	$162.50
Purchase #3	$105.25	11.255%	$117.0959	$117.10	$117.10	$117.10
Purchase #4	$128.57	10.399%	$141.94	$141.94	$141.95	$141.90
Purchase #5	$92.81	8.486%	$100.6859	$100.69	$100.70	$100.70
Purchase #6	$179.93	3.728%	$186.6378	$186.64	$186.65	$186.60
Purchase #7	$183.58	9.359%	$200.7613	$200.76	$200.75	$200.80
7 purchase totals =	$939.53		$1,014.0438	$1,014.05	$1,014.05	$1,014.00