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	$171.50	11.186%	$190.684	$190.68	$190.70	$190.70
Purchase #2	$49.45	6.462%	$52.6455	$52.65	$52.65	$52.60
Purchase #3	$175.83	13.753%	$200.0119	$200.01	$200.00	$200.00
Purchase #4	$210.91	7.582%	$226.9012	$226.90	$226.90	$226.90
Purchase #5	$123.34	3.436%	$127.578	$127.58	$127.60	$127.60
Purchase #6	$96.70	4.216%	$100.7769	$100.78	$100.80	$100.80
Purchase #7	$125.90	9.366%	$137.6918	$137.69	$137.70	$137.70
7 purchase totals =	$953.63		$1,036.2893	$1,036.29	$1,036.35	$1,036.30