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	$174.55	4.683%	$182.7242	$182.72	$182.70	$182.70
Purchase #2	$125.81	4.416%	$131.3658	$131.37	$131.35	$131.40
Purchase #3	$150.94	11.485%	$168.2755	$168.28	$168.30	$168.30
Purchase #4	$80.54	6.319%	$85.6293	$85.63	$85.65	$85.60
Purchase #5	$9.81	5.799%	$10.3789	$10.38	$10.40	$10.40
Purchase #6	$233.83	7.712%	$251.863	$251.86	$251.85	$251.90
Purchase #7	$138.49	9.659%	$151.8667	$151.87	$151.85	$151.90
7 purchase totals =	$913.97		$982.1034	$982.11	$982.10	$982.20