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	$145.83	8.781%	$158.6353	$158.64	$158.65	$158.60
Purchase #2	$205.38	8.750%	$223.3508	$223.35	$223.35	$223.40
Purchase #3	$121.80	3.537%	$126.1081	$126.11	$126.10	$126.10
Purchase #4	$124.50	8.832%	$135.4958	$135.50	$135.50	$135.50
Purchase #5	$95.56	4.491%	$99.8516	$99.85	$99.85	$99.90
Purchase #6	$50.46	11.114%	$56.0681	$56.07	$56.05	$56.10
Purchase #7	$238.79	4.824%	$250.3092	$250.31	$250.30	$250.30
7 purchase totals =	$982.32		$1,049.8189	$1,049.83	$1,049.80	$1,049.90