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	$149.26	10.659%	$165.1696	$165.17	$165.15	$165.20
Purchase #2	$174.87	12.306%	$196.3895	$196.39	$196.40	$196.40
Purchase #3	$159.85	7.456%	$171.7684	$171.77	$171.75	$171.80
Purchase #4	$70.73	8.676%	$76.8665	$76.87	$76.85	$76.90
Purchase #5	$148.89	4.560%	$155.6794	$155.68	$155.70	$155.70
Purchase #6	$117.44	6.214%	$124.7377	$124.74	$124.75	$124.70
Purchase #7	$141.87	10.542%	$156.8259	$156.83	$156.85	$156.80
7 purchase totals =	$962.91		$1,047.4370	$1,047.45	$1,047.45	$1,047.50