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	$122.47	8.342%	$132.6864	$132.69	$132.70	$132.70
Purchase #2	$10.58	8.841%	$11.5154	$11.52	$11.50	$11.50
Purchase #3	$35.78	3.593%	$37.0656	$37.07	$37.05	$37.10
Purchase #4	$144.82	13.630%	$164.559	$164.56	$164.55	$164.60
Purchase #5	$132.75	6.765%	$141.7305	$141.73	$141.75	$141.70
Purchase #6	$162.38	13.604%	$184.4702	$184.47	$184.45	$184.50
Purchase #7	$174.46	12.725%	$196.66	$196.66	$196.65	$196.70
7 purchase totals =	$783.24		$868.6871	$868.70	$868.65	$868.80