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	$178.87	10.288%	$197.2721	$197.27	$197.25	$197.30
Purchase #2	$250.64	10.289%	$276.4283	$276.43	$276.45	$276.40
Purchase #3	$101.77	9.717%	$111.659	$111.66	$111.65	$111.70
Purchase #4	$225.53	7.166%	$241.6915	$241.69	$241.70	$241.70
Purchase #5	$104.31	8.348%	$113.0178	$113.02	$113.00	$113.00
Purchase #6	$10.80	6.655%	$11.5187	$11.52	$11.50	$11.50
Purchase #7	$178.60	10.111%	$196.6582	$196.66	$196.65	$196.70
7 purchase totals =	$1,050.52		$1,148.2456	$1,148.25	$1,148.20	$1,148.30