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	$213.65	8.631%	$232.0901	$232.09	$232.10	$232.10
Purchase #2	$57.42	6.450%	$61.1236	$61.12	$61.10	$61.10
Purchase #3	$26.37	8.210%	$28.535	$28.54	$28.55	$28.50
Purchase #4	$199.52	11.465%	$222.395	$222.40	$222.40	$222.40
Purchase #5	$130.61	6.661%	$139.3099	$139.31	$139.30	$139.30
Purchase #6	$69.61	3.634%	$72.1396	$72.14	$72.15	$72.10
Purchase #7	$56.39	6.156%	$59.8614	$59.86	$59.85	$59.90
7 purchase totals =	$753.57		$815.4546	$815.46	$815.45	$815.40