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	$200.33	5.455%	$211.258	$211.26	$211.25	$211.30
Purchase #2	$94.53	11.422%	$105.3272	$105.33	$105.35	$105.30
Purchase #3	$117.70	4.747%	$123.2872	$123.29	$123.30	$123.30
Purchase #4	$132.38	6.233%	$140.6312	$140.63	$140.65	$140.60
Purchase #5	$233.76	9.319%	$255.5441	$255.54	$255.55	$255.50
Purchase #6	$232.79	10.253%	$256.658	$256.66	$256.65	$256.70
Purchase #7	$73.58	3.329%	$76.0295	$76.03	$76.05	$76.00
7 purchase totals =	$1,085.07		$1,168.7352	$1,168.74	$1,168.80	$1,168.70