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	$161.52	7.551%	$173.7164	$173.72	$173.70	$173.70
Purchase #2	$78.45	10.258%	$86.4974	$86.50	$86.50	$86.50
Purchase #3	$108.90	10.765%	$120.6231	$120.62	$120.60	$120.60
Purchase #4	$139.83	7.815%	$150.7577	$150.76	$150.75	$150.80
Purchase #5	$223.35	8.258%	$241.7942	$241.79	$241.80	$241.80
Purchase #6	$173.95	11.356%	$193.7038	$193.70	$193.70	$193.70
Purchase #7	$36.32	3.390%	$37.5512	$37.55	$37.55	$37.60
7 purchase totals =	$922.32		$1,004.6438	$1,004.64	$1,004.60	$1,004.70