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	$85.27	11.323%	$94.9251	$94.93	$94.95	$94.90
Purchase #2	$16.94	11.697%	$18.9215	$18.92	$18.90	$18.90
Purchase #3	$52.30	4.184%	$54.4882	$54.49	$54.50	$54.50
Purchase #4	$118.89	7.504%	$127.8115	$127.81	$127.80	$127.80
Purchase #5	$49.29	11.639%	$55.0269	$55.03	$55.05	$55.00
Purchase #6	$41.63	8.157%	$45.0258	$45.03	$45.05	$45.00
Purchase #7	$169.54	4.599%	$177.3371	$177.34	$177.35	$177.30
7 purchase totals =	$533.86		$573.5361	$573.55	$573.60	$573.40