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	$60.28	3.634%	$62.4706	$62.47	$62.45	$62.50
Purchase #2	$246.39	3.211%	$254.3016	$254.30	$254.30	$254.30
Purchase #3	$159.46	10.842%	$176.7487	$176.75	$176.75	$176.70
Purchase #4	$248.70	9.200%	$271.5804	$271.58	$271.60	$271.60
Purchase #5	$6.98	6.245%	$7.4159	$7.42	$7.40	$7.40
Purchase #6	$89.89	12.754%	$101.3546	$101.35	$101.35	$101.40
Purchase #7	$248.62	3.191%	$256.5535	$256.55	$256.55	$256.60
7 purchase totals =	$1,060.32		$1,130.4253	$1,130.42	$1,130.40	$1,130.50