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	$62.51	10.633%	$69.1567	$69.16	$69.15	$69.20
Purchase #2	$245.51	5.757%	$259.644	$259.64	$259.65	$259.60
Purchase #3	$193.25	8.391%	$209.4656	$209.47	$209.45	$209.50
Purchase #4	$167.75	6.408%	$178.4994	$178.50	$178.50	$178.50
Purchase #5	$147.51	5.372%	$155.4342	$155.43	$155.45	$155.40
Purchase #6	$139.47	11.247%	$155.1562	$155.16	$155.15	$155.20
Purchase #7	$52.74	3.256%	$54.4572	$54.46	$54.45	$54.50
7 purchase totals =	$1,008.74		$1,081.8133	$1,081.82	$1,081.80	$1,081.90