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	$191.25	12.169%	$214.5232	$214.52	$214.50	$214.50
Purchase #2	$72.56	11.243%	$80.7179	$80.72	$80.70	$80.70
Purchase #3	$59.36	3.752%	$61.5872	$61.59	$61.60	$61.60
Purchase #4	$197.61	6.855%	$211.1562	$211.16	$211.15	$211.20
Purchase #5	$232.54	8.305%	$251.8524	$251.85	$251.85	$251.90
Purchase #6	$112.95	9.549%	$123.7356	$123.74	$123.75	$123.70
Purchase #7	$188.61	10.641%	$208.68	$208.68	$208.70	$208.70
7 purchase totals =	$1,054.88		$1,152.2525	$1,152.26	$1,152.25	$1,152.30