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	$172.91	13.594%	$196.4154	$196.42	$196.40	$196.40
Purchase #2	$194.29	12.756%	$219.0736	$219.07	$219.05	$219.10
Purchase #3	$6.72	12.675%	$7.5718	$7.57	$7.55	$7.60
Purchase #4	$194.29	12.149%	$217.8943	$217.89	$217.90	$217.90
Purchase #5	$188.73	13.530%	$214.2652	$214.27	$214.25	$214.30
Purchase #6	$194.99	13.855%	$222.0059	$222.01	$222.00	$222.00
Purchase #7	$65.39	12.517%	$73.5749	$73.57	$73.55	$73.60
7 purchase totals =	$1,017.32		$1,150.8011	$1,150.80	$1,150.70	$1,150.90