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	$82.93	13.425%	$94.0634	$94.06	$94.05	$94.10
Purchase #2	$160.26	13.615%	$182.0794	$182.08	$182.10	$182.10
Purchase #3	$155.85	11.320%	$173.4922	$173.49	$173.50	$173.50
Purchase #4	$112.89	4.225%	$117.6596	$117.66	$117.65	$117.70
Purchase #5	$204.26	5.242%	$214.9673	$214.97	$214.95	$215.00
Purchase #6	$120.82	8.152%	$130.6692	$130.67	$130.65	$130.70
Purchase #7	$85.59	5.802%	$90.5559	$90.56	$90.55	$90.60
7 purchase totals =	$922.60		$1,003.4870	$1,003.49	$1,003.45	$1,003.70