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	$179.64	9.509%	$196.722	$196.72	$196.70	$196.70
Purchase #2	$173.88	13.612%	$197.5485	$197.55	$197.55	$197.50
Purchase #3	$174.62	9.641%	$191.4551	$191.46	$191.45	$191.50
Purchase #4	$118.77	12.674%	$133.8229	$133.82	$133.80	$133.80
Purchase #5	$224.63	7.652%	$241.8187	$241.82	$241.80	$241.80
Purchase #6	$35.50	13.406%	$40.2591	$40.26	$40.25	$40.30
Purchase #7	$16.61	4.558%	$17.3671	$17.37	$17.35	$17.40
7 purchase totals =	$923.65		$1,018.9934	$1,019.00	$1,018.90	$1,019.00