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	$233.45	11.770%	$260.9271	$260.93	$260.95	$260.90
Purchase #2	$127.25	11.433%	$141.7985	$141.80	$141.80	$141.80
Purchase #3	$62.58	8.584%	$67.9519	$67.95	$67.95	$68.00
Purchase #4	$238.82	10.734%	$264.4549	$264.45	$264.45	$264.50
Purchase #5	$110.77	11.709%	$123.7401	$123.74	$123.75	$123.70
Purchase #6	$65.34	9.859%	$71.7819	$71.78	$71.80	$71.80
Purchase #7	$230.27	12.313%	$258.6231	$258.62	$258.60	$258.60
7 purchase totals =	$1,068.48		$1,189.2775	$1,189.27	$1,189.30	$1,189.30