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	$54.33	11.719%	$60.6969	$60.70	$60.70	$60.70
Purchase #2	$78.84	11.523%	$87.9247	$87.92	$87.90	$87.90
Purchase #3	$213.40	4.255%	$222.4802	$222.48	$222.50	$222.50
Purchase #4	$180.86	8.602%	$196.4176	$196.42	$196.40	$196.40
Purchase #5	$31.92	4.559%	$33.3752	$33.38	$33.40	$33.40
Purchase #6	$96.87	4.142%	$100.8824	$100.88	$100.90	$100.90
Purchase #7	$187.47	3.647%	$194.307	$194.31	$194.30	$194.30
7 purchase totals =	$843.69		$896.0840	$896.09	$896.10	$896.10