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	$225.32	8.838%	$245.2338	$245.23	$245.25	$245.20
Purchase #2	$247.31	9.131%	$269.8919	$269.89	$269.90	$269.90
Purchase #3	$128.55	13.390%	$145.7628	$145.76	$145.75	$145.80
Purchase #4	$165.78	4.164%	$172.6831	$172.68	$172.70	$172.70
Purchase #5	$182.93	3.629%	$189.5685	$189.57	$189.55	$189.60
Purchase #6	$210.60	3.768%	$218.5354	$218.54	$218.55	$218.50
Purchase #7	$225.61	7.478%	$242.4811	$242.48	$242.50	$242.50
7 purchase totals =	$1,386.10		$1,484.1566	$1,484.15	$1,484.20	$1,484.20