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	$182.79	7.683%	$196.8338	$196.83	$196.85	$196.80
Purchase #2	$244.74	11.748%	$273.4921	$273.49	$273.50	$273.50
Purchase #3	$25.38	9.139%	$27.6995	$27.70	$27.70	$27.70
Purchase #4	$144.85	8.473%	$157.1231	$157.12	$157.10	$157.10
Purchase #5	$74.84	4.853%	$78.472	$78.47	$78.45	$78.50
Purchase #6	$158.89	10.267%	$175.2032	$175.20	$175.20	$175.20
Purchase #7	$97.91	4.698%	$102.5098	$102.51	$102.50	$102.50
7 purchase totals =	$929.40		$1,011.3335	$1,011.32	$1,011.30	$1,011.30