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	$184.79	9.243%	$201.8701	$201.87	$201.85	$201.90
Purchase #2	$195.62	13.571%	$222.1676	$222.17	$222.15	$222.20
Purchase #3	$150.85	3.803%	$156.5868	$156.59	$156.60	$156.60
Purchase #4	$52.83	3.327%	$54.5877	$54.59	$54.60	$54.60
Purchase #5	$80.28	12.201%	$90.075	$90.08	$90.10	$90.10
Purchase #6	$231.66	8.719%	$251.8584	$251.86	$251.85	$251.90
Purchase #7	$76.94	11.133%	$85.5057	$85.51	$85.50	$85.50
7 purchase totals =	$972.97		$1,062.6513	$1,062.67	$1,062.65	$1,062.80