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	$149.67	8.268%	$162.0447	$162.04	$162.05	$162.00
Purchase #2	$117.56	6.245%	$124.9016	$124.90	$124.90	$124.90
Purchase #3	$246.88	3.608%	$255.7874	$255.79	$255.80	$255.80
Purchase #4	$46.89	13.319%	$53.1353	$53.14	$53.15	$53.10
Purchase #5	$245.72	9.685%	$269.518	$269.52	$269.50	$269.50
Purchase #6	$108.58	10.163%	$119.615	$119.62	$119.60	$119.60
Purchase #7	$202.59	5.583%	$213.9006	$213.90	$213.90	$213.90
7 purchase totals =	$1,117.89		$1,198.9026	$1,198.91	$1,198.90	$1,198.80