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	$58.55	5.587%	$61.8212	$61.82	$61.80	$61.80
Purchase #2	$241.89	5.161%	$254.3739	$254.37	$254.35	$254.40
Purchase #3	$229.64	11.764%	$256.6548	$256.65	$256.65	$256.70
Purchase #4	$55.52	10.559%	$61.3824	$61.38	$61.40	$61.40
Purchase #5	$94.71	5.693%	$100.1018	$100.10	$100.10	$100.10
Purchase #6	$63.77	4.499%	$66.639	$66.64	$66.65	$66.60
Purchase #7	$221.30	3.294%	$228.5896	$228.59	$228.60	$228.60
7 purchase totals =	$965.38		$1,029.5627	$1,029.55	$1,029.55	$1,029.60