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	$54.41	10.749%	$60.2585	$60.26	$60.25	$60.30
Purchase #2	$21.90	3.488%	$22.6639	$22.66	$22.65	$22.70
Purchase #3	$136.85	3.419%	$141.5289	$141.53	$141.55	$141.50
Purchase #4	$165.61	10.256%	$182.595	$182.60	$182.60	$182.60
Purchase #5	$226.75	9.612%	$248.5452	$248.55	$248.55	$248.50
Purchase #6	$100.77	11.409%	$112.2668	$112.27	$112.25	$112.30
Purchase #7	$176.72	10.114%	$194.5935	$194.59	$194.60	$194.60
7 purchase totals =	$883.01		$962.4518	$962.46	$962.45	$962.50