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	$176.95	11.257%	$196.8693	$196.87	$196.85	$196.90
Purchase #2	$53.47	4.690%	$55.9777	$55.98	$56.00	$56.00
Purchase #3	$236.70	9.449%	$259.0658	$259.07	$259.05	$259.10
Purchase #4	$162.62	6.372%	$172.9821	$172.98	$173.00	$173.00
Purchase #5	$174.87	12.266%	$196.3196	$196.32	$196.30	$196.30
Purchase #6	$84.68	5.448%	$89.2934	$89.29	$89.30	$89.30
Purchase #7	$90.35	9.871%	$99.2684	$99.27	$99.25	$99.30
7 purchase totals =	$979.64		$1,069.7763	$1,069.78	$1,069.75	$1,069.90