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	$182.27	7.800%	$196.4871	$196.49	$196.50	$196.50
Purchase #2	$131.66	7.322%	$141.3001	$141.30	$141.30	$141.30
Purchase #3	$92.72	3.819%	$96.261	$96.26	$96.25	$96.30
Purchase #4	$43.34	12.198%	$48.6266	$48.63	$48.65	$48.60
Purchase #5	$231.87	3.838%	$240.7692	$240.77	$240.75	$240.80
Purchase #6	$82.88	9.859%	$91.0511	$91.05	$91.05	$91.10
Purchase #7	$52.38	4.214%	$54.5873	$54.59	$54.60	$54.60
7 purchase totals =	$817.12		$869.0824	$869.09	$869.10	$869.20