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	$148.59	9.737%	$163.0582	$163.06	$163.05	$163.10
Purchase #2	$202.62	4.371%	$211.4765	$211.48	$211.50	$211.50
Purchase #3	$54.80	8.331%	$59.3654	$59.37	$59.35	$59.40
Purchase #4	$227.52	7.602%	$244.8161	$244.82	$244.80	$244.80
Purchase #5	$248.25	3.311%	$256.4696	$256.47	$256.45	$256.50
Purchase #6	$29.25	12.601%	$32.9358	$32.94	$32.95	$32.90
Purchase #7	$200.49	8.522%	$217.5758	$217.58	$217.60	$217.60
7 purchase totals =	$1,111.52		$1,185.6974	$1,185.72	$1,185.70	$1,185.80