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	$232.37	13.152%	$262.9313	$262.93	$262.95	$262.90
Purchase #2	$79.93	12.220%	$89.6974	$89.70	$89.70	$89.70
Purchase #3	$145.60	6.786%	$155.4804	$155.48	$155.50	$155.50
Purchase #4	$76.65	3.659%	$79.4546	$79.45	$79.45	$79.50
Purchase #5	$160.48	8.128%	$173.5238	$173.52	$173.50	$173.50
Purchase #6	$166.59	4.508%	$174.0999	$174.10	$174.10	$174.10
Purchase #7	$59.98	9.131%	$65.4568	$65.46	$65.45	$65.50
7 purchase totals =	$921.60		$1,000.6442	$1,000.64	$1,000.65	$1,000.70