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	$169.67	10.256%	$187.0714	$187.07	$187.05	$187.10
Purchase #2	$232.88	5.489%	$245.6628	$245.66	$245.65	$245.70
Purchase #3	$34.91	7.277%	$37.4504	$37.45	$37.45	$37.50
Purchase #4	$36.85	11.774%	$41.1887	$41.19	$41.20	$41.20
Purchase #5	$189.75	5.661%	$200.4917	$200.49	$200.50	$200.50
Purchase #6	$244.83	4.359%	$255.5021	$255.50	$255.50	$255.50
Purchase #7	$225.39	11.667%	$251.6863	$251.69	$251.70	$251.70
7 purchase totals =	$1,134.28		$1,219.0534	$1,219.05	$1,219.05	$1,219.20