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	$130.60	11.430%	$145.5276	$145.53	$145.55	$145.50
Purchase #2	$25.31	9.173%	$27.6317	$27.63	$27.65	$27.60
Purchase #3	$104.78	6.792%	$111.8967	$111.90	$111.90	$111.90
Purchase #4	$37.74	8.855%	$41.0819	$41.08	$41.10	$41.10
Purchase #5	$225.37	5.437%	$237.6234	$237.62	$237.60	$237.60
Purchase #6	$233.81	10.650%	$258.7108	$258.71	$258.70	$258.70
Purchase #7	$227.94	12.354%	$256.0997	$256.10	$256.10	$256.10
7 purchase totals =	$985.55		$1,078.5718	$1,078.57	$1,078.60	$1,078.50