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	$225.75	3.424%	$233.4797	$233.48	$233.50	$233.50
Purchase #2	$200.56	13.431%	$227.4972	$227.50	$227.50	$227.50
Purchase #3	$212.89	4.627%	$222.7404	$222.74	$222.75	$222.70
Purchase #4	$130.77	9.566%	$143.2795	$143.28	$143.30	$143.30
Purchase #5	$32.72	8.640%	$35.547	$35.55	$35.55	$35.50
Purchase #6	$162.39	4.126%	$169.0902	$169.09	$169.10	$169.10
Purchase #7	$62.31	6.386%	$66.2891	$66.29	$66.30	$66.30
7 purchase totals =	$1,027.39		$1,097.9231	$1,097.93	$1,098.00	$1,097.90