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	$213.63	9.481%	$233.8843	$233.88	$233.90	$233.90
Purchase #2	$105.42	11.456%	$117.4969	$117.50	$117.50	$117.50
Purchase #3	$179.97	11.280%	$200.2706	$200.27	$200.25	$200.30
Purchase #4	$205.35	3.487%	$212.5106	$212.51	$212.50	$212.50
Purchase #5	$96.41	12.688%	$108.6425	$108.64	$108.65	$108.60
Purchase #6	$113.94	9.650%	$124.9352	$124.94	$124.95	$124.90
Purchase #7	$183.73	8.344%	$199.0604	$199.06	$199.05	$199.10
7 purchase totals =	$1,098.45		$1,196.8005	$1,196.80	$1,196.80	$1,196.80