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	$68.95	12.196%	$77.3591	$77.36	$77.35	$77.40
Purchase #2	$83.32	7.372%	$89.4624	$89.46	$89.45	$89.50
Purchase #3	$200.75	10.611%	$222.0516	$222.05	$222.05	$222.10
Purchase #4	$79.93	9.237%	$87.3131	$87.31	$87.30	$87.30
Purchase #5	$205.58	9.777%	$225.6796	$225.68	$225.70	$225.70
Purchase #6	$87.91	8.125%	$95.0527	$95.05	$95.05	$95.10
Purchase #7	$200.59	13.407%	$227.4831	$227.48	$227.50	$227.50
7 purchase totals =	$927.03		$1,024.4016	$1,024.39	$1,024.40	$1,024.60