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	$189.81	3.344%	$196.1572	$196.16	$196.15	$196.20
Purchase #2	$103.90	12.399%	$116.7826	$116.78	$116.80	$116.80
Purchase #3	$159.47	7.772%	$171.864	$171.86	$171.85	$171.90
Purchase #4	$87.41	8.119%	$94.5068	$94.51	$94.50	$94.50
Purchase #5	$203.86	6.837%	$217.7979	$217.80	$217.80	$217.80
Purchase #6	$240.94	5.434%	$254.0327	$254.03	$254.05	$254.00
Purchase #7	$199.41	4.477%	$208.3376	$208.34	$208.35	$208.30
7 purchase totals =	$1,184.80		$1,259.4788	$1,259.48	$1,259.50	$1,259.50