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	$96.94	8.562%	$105.24	$105.24	$105.25	$105.20
Purchase #2	$63.91	11.122%	$71.0181	$71.02	$71.00	$71.00
Purchase #3	$126.72	12.436%	$142.4789	$142.48	$142.50	$142.50
Purchase #4	$241.48	10.509%	$266.8571	$266.86	$266.85	$266.90
Purchase #5	$54.46	11.433%	$60.6864	$60.69	$60.70	$60.70
Purchase #6	$163.59	9.213%	$178.6615	$178.66	$178.65	$178.70
Purchase #7	$242.79	11.145%	$269.8489	$269.85	$269.85	$269.80
7 purchase totals =	$989.89		$1,094.7909	$1,094.80	$1,094.80	$1,094.80