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	$126.96	5.192%	$133.5518	$133.55	$133.55	$133.60
Purchase #2	$121.66	4.598%	$127.2539	$127.25	$127.25	$127.30
Purchase #3	$132.25	4.388%	$138.0531	$138.05	$138.05	$138.10
Purchase #4	$68.48	4.466%	$71.5383	$71.54	$71.55	$71.50
Purchase #5	$61.78	3.419%	$63.8923	$63.89	$63.90	$63.90
Purchase #6	$114.91	6.498%	$122.3769	$122.38	$122.40	$122.40
Purchase #7	$9.91	8.821%	$10.7842	$10.78	$10.80	$10.80
7 purchase totals =	$635.95		$667.4505	$667.44	$667.50	$667.60