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	$217.58	7.387%	$233.6526	$233.65	$233.65	$233.70
Purchase #2	$197.59	6.129%	$209.7003	$209.70	$209.70	$209.70
Purchase #3	$40.87	11.255%	$45.4699	$45.47	$45.45	$45.50
Purchase #4	$153.59	11.464%	$171.1976	$171.20	$171.20	$171.20
Purchase #5	$156.78	5.410%	$165.2618	$165.26	$165.25	$165.30
Purchase #6	$122.44	7.259%	$131.3279	$131.33	$131.35	$131.30
Purchase #7	$50.57	4.533%	$52.8623	$52.86	$52.85	$52.90
7 purchase totals =	$939.42		$1,009.4724	$1,009.47	$1,009.45	$1,009.60