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	$153.57	12.678%	$173.0396	$173.04	$173.05	$173.00
Purchase #2	$171.69	13.575%	$194.9969	$195.00	$195.00	$195.00
Purchase #3	$139.27	3.248%	$143.7935	$143.79	$143.80	$143.80
Purchase #4	$86.59	5.667%	$91.4971	$91.50	$91.50	$91.50
Purchase #5	$105.86	11.361%	$117.8868	$117.89	$117.90	$117.90
Purchase #6	$223.69	9.345%	$244.5938	$244.59	$244.60	$244.60
Purchase #7	$208.25	7.138%	$223.1149	$223.11	$223.10	$223.10
7 purchase totals =	$1,088.92		$1,188.9226	$1,188.92	$1,188.95	$1,188.90