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	$119.39	11.475%	$133.09	$133.09	$133.10	$133.10
Purchase #2	$148.71	4.416%	$155.277	$155.28	$155.30	$155.30
Purchase #3	$95.97	4.493%	$100.2819	$100.28	$100.30	$100.30
Purchase #4	$246.38	9.580%	$269.9832	$269.98	$270.00	$270.00
Purchase #5	$141.65	10.283%	$156.2159	$156.22	$156.20	$156.20
Purchase #6	$155.30	13.744%	$176.6444	$176.64	$176.65	$176.60
Purchase #7	$62.41	12.715%	$70.3454	$70.35	$70.35	$70.30
7 purchase totals =	$969.81		$1,061.8378	$1,061.84	$1,061.90	$1,061.80