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	$148.92	8.628%	$161.7688	$161.77	$161.75	$161.80
Purchase #2	$41.51	5.769%	$43.9047	$43.90	$43.90	$43.90
Purchase #3	$245.66	12.472%	$276.2987	$276.30	$276.30	$276.30
Purchase #4	$92.94	5.821%	$98.35	$98.35	$98.35	$98.40
Purchase #5	$68.95	5.166%	$72.512	$72.51	$72.50	$72.50
Purchase #6	$212.96	5.103%	$223.8273	$223.83	$223.85	$223.80
Purchase #7	$143.86	7.475%	$154.6135	$154.61	$154.60	$154.60
7 purchase totals =	$954.80		$1,031.2750	$1,031.27	$1,031.25	$1,031.30