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	$58.48	11.103%	$64.973	$64.97	$64.95	$65.00
Purchase #2	$64.87	10.478%	$71.6671	$71.67	$71.65	$71.70
Purchase #3	$52.39	5.527%	$55.2856	$55.29	$55.30	$55.30
Purchase #4	$165.76	13.559%	$188.2354	$188.24	$188.25	$188.20
Purchase #5	$234.75	6.718%	$250.5205	$250.52	$250.50	$250.50
Purchase #6	$62.52	5.396%	$65.8936	$65.89	$65.90	$65.90
Purchase #7	$246.34	3.633%	$255.2895	$255.29	$255.30	$255.30
7 purchase totals =	$885.11		$951.8647	$951.87	$951.85	$951.90