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	$119.53	10.165%	$131.6802	$131.68	$131.70	$131.70
Purchase #2	$12.49	13.667%	$14.197	$14.20	$14.20	$14.20
Purchase #3	$215.27	13.375%	$244.0624	$244.06	$244.05	$244.10
Purchase #4	$238.61	11.484%	$266.012	$266.01	$266.00	$266.00
Purchase #5	$112.34	6.566%	$119.7162	$119.72	$119.70	$119.70
Purchase #6	$161.92	4.841%	$169.7585	$169.76	$169.75	$169.80
Purchase #7	$104.29	6.507%	$111.0762	$111.08	$111.10	$111.10
7 purchase totals =	$964.45		$1,056.5025	$1,056.51	$1,056.50	$1,056.60