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	$105.41	6.226%	$111.9728	$111.97	$111.95	$112.00
Purchase #2	$249.40	5.715%	$263.6532	$263.65	$263.65	$263.70
Purchase #3	$82.77	5.548%	$87.3621	$87.36	$87.35	$87.40
Purchase #4	$143.58	8.293%	$155.4871	$155.49	$155.50	$155.50
Purchase #5	$232.82	12.631%	$262.2275	$262.23	$262.25	$262.20
Purchase #6	$150.94	13.643%	$171.5327	$171.53	$171.55	$171.50
Purchase #7	$133.80	8.102%	$144.6405	$144.64	$144.65	$144.60
7 purchase totals =	$1,098.72		$1,196.8759	$1,196.87	$1,196.90	$1,196.90