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	$151.71	6.697%	$161.87	$161.87	$161.85	$161.90
Purchase #2	$113.29	6.153%	$120.2607	$120.26	$120.25	$120.30
Purchase #3	$77.89	11.336%	$86.7196	$86.72	$86.70	$86.70
Purchase #4	$183.73	13.378%	$208.3094	$208.31	$208.30	$208.30
Purchase #5	$113.60	8.518%	$123.2764	$123.28	$123.30	$123.30
Purchase #6	$231.38	4.123%	$240.9198	$240.92	$240.90	$240.90
Purchase #7	$94.76	10.346%	$104.5639	$104.56	$104.55	$104.60
7 purchase totals =	$966.36		$1,045.9198	$1,045.92	$1,045.85	$1,046.00