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	$225.57	12.456%	$253.667	$253.67	$253.65	$253.70
Purchase #2	$152.57	13.576%	$173.2829	$173.28	$173.30	$173.30
Purchase #3	$201.90	11.679%	$225.4799	$225.48	$225.50	$225.50
Purchase #4	$250.90	5.222%	$264.002	$264.00	$264.00	$264.00
Purchase #5	$105.57	10.497%	$116.6517	$116.65	$116.65	$116.70
Purchase #6	$154.41	8.235%	$167.1257	$167.13	$167.15	$167.10
Purchase #7	$187.77	11.732%	$209.7992	$209.80	$209.80	$209.80
7 purchase totals =	$1,278.69		$1,410.0084	$1,410.01	$1,410.05	$1,410.10