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	$215.63	9.315%	$235.7159	$235.72	$235.70	$235.70
Purchase #2	$79.53	4.269%	$82.9251	$82.93	$82.95	$82.90
Purchase #3	$49.51	4.300%	$51.6389	$51.64	$51.65	$51.60
Purchase #4	$34.97	12.817%	$39.4521	$39.45	$39.45	$39.50
Purchase #5	$103.51	5.633%	$109.3407	$109.34	$109.35	$109.30
Purchase #6	$114.66	11.185%	$127.4847	$127.48	$127.50	$127.50
Purchase #7	$126.67	11.702%	$141.4929	$141.49	$141.50	$141.50
7 purchase totals =	$724.48		$788.0503	$788.05	$788.10	$788.00