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	$127.43	3.356%	$131.7066	$131.71	$131.70	$131.70
Purchase #2	$137.46	13.314%	$155.7614	$155.76	$155.75	$155.80
Purchase #3	$86.52	12.257%	$97.1248	$97.12	$97.10	$97.10
Purchase #4	$176.43	11.490%	$196.7018	$196.70	$196.70	$196.70
Purchase #5	$30.67	3.161%	$31.6395	$31.64	$31.65	$31.60
Purchase #6	$237.60	6.522%	$253.0963	$253.10	$253.10	$253.10
Purchase #7	$141.93	11.203%	$157.8304	$157.83	$157.85	$157.80
7 purchase totals =	$938.04		$1,023.8608	$1,023.86	$1,023.85	$1,023.80