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	$67.35	6.539%	$71.754	$71.75	$71.75	$71.80
Purchase #2	$50.43	13.339%	$57.1569	$57.16	$57.15	$57.20
Purchase #3	$143.44	5.317%	$151.0667	$151.07	$151.05	$151.10
Purchase #4	$217.97	8.306%	$236.0746	$236.07	$236.05	$236.10
Purchase #5	$190.50	5.403%	$200.7927	$200.79	$200.80	$200.80
Purchase #6	$111.70	6.853%	$119.3548	$119.35	$119.35	$119.40
Purchase #7	$173.67	4.295%	$181.1291	$181.13	$181.15	$181.10
7 purchase totals =	$955.06		$1,017.3288	$1,017.32	$1,017.30	$1,017.50