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	$67.26	12.752%	$75.837	$75.84	$75.85	$75.80
Purchase #2	$33.82	10.844%	$37.4874	$37.49	$37.50	$37.50
Purchase #3	$88.70	13.473%	$100.6506	$100.65	$100.65	$100.70
Purchase #4	$126.41	4.483%	$132.077	$132.08	$132.10	$132.10
Purchase #5	$43.38	7.517%	$46.6409	$46.64	$46.65	$46.60
Purchase #6	$6.46	4.779%	$6.7687	$6.77	$6.75	$6.80
Purchase #7	$77.34	10.361%	$85.3532	$85.35	$85.35	$85.40
7 purchase totals =	$443.37		$484.8148	$484.82	$484.85	$484.90