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	$88.36	9.749%	$96.9742	$96.97	$96.95	$97.00
Purchase #2	$159.89	5.378%	$168.4889	$168.49	$168.50	$168.50
Purchase #3	$94.96	4.329%	$99.0708	$99.07	$99.05	$99.10
Purchase #4	$237.39	8.737%	$258.1308	$258.13	$258.15	$258.10
Purchase #5	$56.81	7.520%	$61.0821	$61.08	$61.10	$61.10
Purchase #6	$160.78	10.180%	$177.1474	$177.15	$177.15	$177.10
Purchase #7	$215.98	7.340%	$231.8329	$231.83	$231.85	$231.80
7 purchase totals =	$1,014.17		$1,092.7271	$1,092.72	$1,092.75	$1,092.70