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	$148.40	10.595%	$164.123	$164.12	$164.10	$164.10
Purchase #2	$56.95	8.145%	$61.5886	$61.59	$61.60	$61.60
Purchase #3	$181.57	4.780%	$190.249	$190.25	$190.25	$190.20
Purchase #4	$154.85	12.123%	$173.6225	$173.62	$173.60	$173.60
Purchase #5	$18.48	12.792%	$20.844	$20.84	$20.85	$20.80
Purchase #6	$55.57	10.659%	$61.4932	$61.49	$61.50	$61.50
Purchase #7	$169.83	6.262%	$180.4648	$180.46	$180.45	$180.50
7 purchase totals =	$785.65		$852.3851	$852.37	$852.35	$852.30