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	$182.97	7.136%	$196.0267	$196.03	$196.05	$196.00
Purchase #2	$51.95	13.612%	$59.0214	$59.02	$59.00	$59.00
Purchase #3	$77.88	6.737%	$83.1268	$83.13	$83.15	$83.10
Purchase #4	$177.98	6.389%	$189.3511	$189.35	$189.35	$189.40
Purchase #5	$46.40	11.276%	$51.6321	$51.63	$51.65	$51.60
Purchase #6	$135.69	11.508%	$151.3052	$151.31	$151.30	$151.30
Purchase #7	$113.52	8.678%	$123.3713	$123.37	$123.35	$123.40
7 purchase totals =	$786.39		$853.8346	$853.84	$853.85	$853.80