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	$242.53	7.191%	$259.9703	$259.97	$259.95	$260.00
Purchase #2	$126.82	3.861%	$131.7165	$131.72	$131.70	$131.70
Purchase #3	$248.56	6.588%	$264.9351	$264.94	$264.95	$264.90
Purchase #4	$214.40	11.829%	$239.7614	$239.76	$239.75	$239.80
Purchase #5	$54.29	4.146%	$56.5409	$56.54	$56.55	$56.50
Purchase #6	$114.98	7.853%	$124.0094	$124.01	$124.00	$124.00
Purchase #7	$107.35	11.256%	$119.4333	$119.43	$119.45	$119.40
7 purchase totals =	$1,108.93		$1,196.3669	$1,196.37	$1,196.35	$1,196.30