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	$215.63	5.580%	$227.6622	$227.66	$227.65	$227.70
Purchase #2	$77.46	9.186%	$84.5755	$84.58	$84.60	$84.60
Purchase #3	$18.70	9.133%	$20.4079	$20.41	$20.40	$20.40
Purchase #4	$182.42	3.529%	$188.8576	$188.86	$188.85	$188.90
Purchase #5	$187.39	4.663%	$196.128	$196.13	$196.15	$196.10
Purchase #6	$169.32	11.770%	$189.249	$189.25	$189.25	$189.20
Purchase #7	$146.72	12.831%	$165.5456	$165.55	$165.55	$165.50
7 purchase totals =	$997.64		$1,072.4258	$1,072.44	$1,072.45	$1,072.40