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	$214.71	10.199%	$236.6083	$236.61	$236.60	$236.60
Purchase #2	$9.55	12.538%	$10.7474	$10.75	$10.75	$10.70
Purchase #3	$106.83	4.124%	$111.2357	$111.24	$111.25	$111.20
Purchase #4	$42.30	8.146%	$45.7458	$45.75	$45.75	$45.70
Purchase #5	$219.89	9.868%	$241.5887	$241.59	$241.60	$241.60
Purchase #6	$89.50	6.394%	$95.2226	$95.22	$95.20	$95.20
Purchase #7	$37.61	10.867%	$41.6971	$41.70	$41.70	$41.70
7 purchase totals =	$720.39		$782.8456	$782.86	$782.85	$782.70