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	$190.95	12.462%	$214.7462	$214.75	$214.75	$214.70
Purchase #2	$125.28	4.774%	$131.2609	$131.26	$131.25	$131.30
Purchase #3	$100.62	10.734%	$111.4206	$111.42	$111.40	$111.40
Purchase #4	$91.51	11.810%	$102.3173	$102.32	$102.30	$102.30
Purchase #5	$228.45	10.734%	$252.9718	$252.97	$252.95	$253.00
Purchase #6	$229.90	3.731%	$238.4776	$238.48	$238.50	$238.50
Purchase #7	$193.76	9.142%	$211.4735	$211.47	$211.45	$211.50
7 purchase totals =	$1,160.47		$1,262.6679	$1,262.67	$1,262.60	$1,262.70