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	$57.72	5.305%	$60.782	$60.78	$60.80	$60.80
Purchase #2	$196.91	6.359%	$209.4315	$209.43	$209.45	$209.40
Purchase #3	$214.64	3.634%	$222.44	$222.44	$222.45	$222.40
Purchase #4	$51.83	4.536%	$54.181	$54.18	$54.20	$54.20
Purchase #5	$201.81	10.787%	$223.5792	$223.58	$223.60	$223.60
Purchase #6	$192.81	3.177%	$198.9356	$198.94	$198.95	$198.90
Purchase #7	$200.81	7.478%	$215.8266	$215.83	$215.85	$215.80
7 purchase totals =	$1,116.53		$1,185.1759	$1,185.18	$1,185.30	$1,185.10