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	$87.54	9.526%	$95.8791	$95.88	$95.90	$95.90
Purchase #2	$93.81	12.508%	$105.5438	$105.54	$105.55	$105.50
Purchase #3	$235.49	7.622%	$253.439	$253.44	$253.45	$253.40
Purchase #4	$233.47	12.869%	$263.5153	$263.52	$263.50	$263.50
Purchase #5	$76.73	6.174%	$81.4673	$81.47	$81.45	$81.50
Purchase #6	$208.69	10.610%	$230.832	$230.83	$230.85	$230.80
Purchase #7	$26.60	7.604%	$28.6227	$28.62	$28.60	$28.60
7 purchase totals =	$962.33		$1,059.2992	$1,059.30	$1,059.30	$1,059.20