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	$157.52	9.354%	$172.2544	$172.25	$172.25	$172.30
Purchase #2	$35.81	9.206%	$39.1067	$39.11	$39.10	$39.10
Purchase #3	$224.38	11.374%	$249.901	$249.90	$249.90	$249.90
Purchase #4	$218.67	12.245%	$245.4461	$245.45	$245.45	$245.40
Purchase #5	$215.46	4.863%	$225.9378	$225.94	$225.95	$225.90
Purchase #6	$11.38	6.349%	$12.1025	$12.10	$12.10	$12.10
Purchase #7	$211.68	5.531%	$223.388	$223.39	$223.40	$223.40
7 purchase totals =	$1,074.90		$1,168.1365	$1,168.14	$1,168.15	$1,168.10