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	$190.40	3.431%	$196.9326	$196.93	$196.95	$196.90
Purchase #2	$203.55	5.197%	$214.1285	$214.13	$214.15	$214.10
Purchase #3	$123.33	4.222%	$128.537	$128.54	$128.55	$128.50
Purchase #4	$126.90	12.336%	$142.5544	$142.55	$142.55	$142.60
Purchase #5	$52.54	11.529%	$58.5973	$58.60	$58.60	$58.60
Purchase #6	$41.46	13.745%	$47.1587	$47.16	$47.15	$47.20
Purchase #7	$141.97	5.352%	$149.5682	$149.57	$149.55	$149.60
7 purchase totals =	$880.15		$937.4767	$937.48	$937.50	$937.50