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	$106.63	4.826%	$111.776	$111.78	$111.80	$111.80
Purchase #2	$93.66	3.594%	$97.0261	$97.03	$97.05	$97.00
Purchase #3	$59.47	7.591%	$63.9844	$63.98	$64.00	$64.00
Purchase #4	$220.97	11.153%	$245.6148	$245.61	$245.60	$245.60
Purchase #5	$216.88	12.573%	$244.1483	$244.15	$244.15	$244.10
Purchase #6	$140.32	10.488%	$155.0368	$155.04	$155.05	$155.00
Purchase #7	$156.81	7.206%	$168.1097	$168.11	$168.10	$168.10
7 purchase totals =	$994.74		$1,085.6961	$1,085.70	$1,085.75	$1,085.60