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	$217.57	4.785%	$227.9807	$227.98	$228.00	$228.00
Purchase #2	$219.65	6.735%	$234.4434	$234.44	$234.45	$234.40
Purchase #3	$72.83	7.351%	$78.1837	$78.18	$78.20	$78.20
Purchase #4	$49.95	5.399%	$52.6468	$52.65	$52.65	$52.60
Purchase #5	$210.70	7.856%	$227.2526	$227.25	$227.25	$227.30
Purchase #6	$225.47	8.417%	$244.4478	$244.45	$244.45	$244.40
Purchase #7	$27.69	6.763%	$29.5627	$29.56	$29.55	$29.60
7 purchase totals =	$1,023.86		$1,094.5177	$1,094.51	$1,094.55	$1,094.50