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	$81.78	4.211%	$85.2238	$85.22	$85.20	$85.20
Purchase #2	$110.61	4.733%	$115.8452	$115.85	$115.85	$115.80
Purchase #3	$193.61	6.107%	$205.4338	$205.43	$205.45	$205.40
Purchase #4	$90.70	5.256%	$95.4672	$95.47	$95.45	$95.50
Purchase #5	$177.65	10.539%	$196.3725	$196.37	$196.35	$196.40
Purchase #6	$162.84	7.293%	$174.7159	$174.72	$174.70	$174.70
Purchase #7	$156.49	3.469%	$161.9186	$161.92	$161.90	$161.90
7 purchase totals =	$973.68		$1,034.9770	$1,034.98	$1,034.90	$1,034.90