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	$86.62	10.122%	$95.3877	$95.39	$95.40	$95.40
Purchase #2	$229.52	11.741%	$256.4679	$256.47	$256.45	$256.50
Purchase #3	$211.57	6.515%	$225.3538	$225.35	$225.35	$225.40
Purchase #4	$82.32	9.436%	$90.0877	$90.09	$90.10	$90.10
Purchase #5	$230.51	8.622%	$250.3846	$250.38	$250.40	$250.40
Purchase #6	$113.58	7.778%	$122.4143	$122.41	$122.40	$122.40
Purchase #7	$71.88	6.171%	$76.3157	$76.32	$76.30	$76.30
7 purchase totals =	$1,026.00		$1,116.4117	$1,116.41	$1,116.40	$1,116.50