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	$177.72	7.855%	$191.6799	$191.68	$191.70	$191.70
Purchase #2	$111.77	11.414%	$124.5274	$124.53	$124.55	$124.50
Purchase #3	$51.85	3.107%	$53.461	$53.46	$53.45	$53.50
Purchase #4	$206.27	8.843%	$224.5105	$224.51	$224.50	$224.50
Purchase #5	$181.32	4.860%	$190.1322	$190.13	$190.15	$190.10
Purchase #6	$232.65	7.849%	$250.9107	$250.91	$250.90	$250.90
Purchase #7	$23.85	7.423%	$25.6204	$25.62	$25.60	$25.60
7 purchase totals =	$985.43		$1,060.8421	$1,060.84	$1,060.85	$1,060.80