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	$57.97	3.379%	$59.9288	$59.93	$59.95	$59.90
Purchase #2	$232.60	13.550%	$264.1173	$264.12	$264.10	$264.10
Purchase #3	$154.50	9.806%	$169.6503	$169.65	$169.65	$169.70
Purchase #4	$157.49	11.608%	$175.7714	$175.77	$175.75	$175.80
Purchase #5	$56.55	7.159%	$60.5984	$60.60	$60.60	$60.60
Purchase #6	$195.90	13.221%	$221.7999	$221.80	$221.80	$221.80
Purchase #7	$106.99	4.123%	$111.4012	$111.40	$111.40	$111.40
7 purchase totals =	$962.00		$1,063.2673	$1,063.27	$1,063.25	$1,063.30