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	$151.70	9.208%	$165.6685	$165.67	$165.65	$165.70
Purchase #2	$11.80	9.234%	$12.8896	$12.89	$12.90	$12.90
Purchase #3	$193.81	3.477%	$200.5488	$200.55	$200.55	$200.50
Purchase #4	$54.43	4.240%	$56.7378	$56.74	$56.75	$56.70
Purchase #5	$247.59	3.120%	$255.3148	$255.31	$255.30	$255.30
Purchase #6	$209.83	12.668%	$236.4113	$236.41	$236.40	$236.40
Purchase #7	$129.60	11.738%	$144.8124	$144.81	$144.80	$144.80
7 purchase totals =	$998.76		$1,072.3832	$1,072.38	$1,072.35	$1,072.30