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	$209.26	9.401%	$228.9325	$228.93	$228.95	$228.90
Purchase #2	$233.92	8.212%	$253.1295	$253.13	$253.15	$253.10
Purchase #3	$51.69	10.437%	$57.0849	$57.08	$57.10	$57.10
Purchase #4	$39.76	6.687%	$42.4188	$42.42	$42.40	$42.40
Purchase #5	$172.37	10.540%	$190.5378	$190.54	$190.55	$190.50
Purchase #6	$116.83	5.131%	$122.8245	$122.82	$122.80	$122.80
Purchase #7	$208.44	7.111%	$223.2622	$223.26	$223.25	$223.30
7 purchase totals =	$1,032.27		$1,118.1902	$1,118.18	$1,118.20	$1,118.10