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	$68.33	5.342%	$71.9802	$71.98	$72.00	$72.00
Purchase #2	$27.53	4.166%	$28.6769	$28.68	$28.70	$28.70
Purchase #3	$135.70	11.716%	$151.5986	$151.60	$151.60	$151.60
Purchase #4	$39.32	11.302%	$43.7639	$43.76	$43.75	$43.80
Purchase #5	$243.64	5.758%	$257.6688	$257.67	$257.65	$257.70
Purchase #6	$60.59	12.760%	$68.3213	$68.32	$68.30	$68.30
Purchase #7	$92.62	13.526%	$105.1478	$105.15	$105.15	$105.10
7 purchase totals =	$667.73		$727.1575	$727.16	$727.15	$727.20