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	$147.45	8.280%	$159.6589	$159.66	$159.65	$159.70
Purchase #2	$95.54	5.314%	$100.617	$100.62	$100.60	$100.60
Purchase #3	$186.78	7.228%	$200.2805	$200.28	$200.30	$200.30
Purchase #4	$129.88	6.231%	$137.9728	$137.97	$137.95	$138.00
Purchase #5	$107.34	4.281%	$111.9352	$111.94	$111.95	$111.90
Purchase #6	$206.71	3.313%	$213.5583	$213.56	$213.55	$213.60
Purchase #7	$173.70	6.390%	$184.7994	$184.80	$184.80	$184.80
7 purchase totals =	$1,047.40		$1,108.8221	$1,108.83	$1,108.80	$1,108.90