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	$161.97	4.192%	$168.7598	$168.76	$168.75	$168.80
Purchase #2	$12.76	9.424%	$13.9625	$13.96	$13.95	$14.00
Purchase #3	$235.56	9.198%	$257.2268	$257.23	$257.25	$257.20
Purchase #4	$69.49	3.476%	$71.9055	$71.91	$71.90	$71.90
Purchase #5	$208.62	7.772%	$224.8339	$224.83	$224.85	$224.80
Purchase #6	$138.38	10.500%	$152.9099	$152.91	$152.90	$152.90
Purchase #7	$224.41	13.780%	$255.3337	$255.33	$255.35	$255.30
7 purchase totals =	$1,051.19		$1,144.9321	$1,144.93	$1,144.95	$1,144.90