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	$126.58	9.559%	$138.6798	$138.68	$138.70	$138.70
Purchase #2	$85.74	5.497%	$90.4531	$90.45	$90.45	$90.50
Purchase #3	$53.64	7.449%	$57.6356	$57.64	$57.65	$57.60
Purchase #4	$190.75	4.806%	$199.9174	$199.92	$199.90	$199.90
Purchase #5	$156.56	4.789%	$164.0577	$164.06	$164.05	$164.10
Purchase #6	$113.56	11.682%	$126.8261	$126.83	$126.85	$126.80
Purchase #7	$233.31	6.254%	$247.9012	$247.90	$247.90	$247.90
7 purchase totals =	$960.14		$1,025.4709	$1,025.48	$1,025.50	$1,025.50