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	$155.54	4.348%	$162.3029	$162.30	$162.30	$162.30
Purchase #2	$212.81	5.527%	$224.572	$224.57	$224.55	$224.60
Purchase #3	$100.97	6.719%	$107.7542	$107.75	$107.75	$107.80
Purchase #4	$248.66	8.158%	$268.9457	$268.95	$268.95	$268.90
Purchase #5	$47.98	13.539%	$54.476	$54.48	$54.50	$54.50
Purchase #6	$103.80	7.803%	$111.8995	$111.90	$111.90	$111.90
Purchase #7	$134.81	13.213%	$152.6224	$152.62	$152.60	$152.60
7 purchase totals =	$1,004.57		$1,082.5727	$1,082.57	$1,082.55	$1,082.60