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	$211.43	11.468%	$235.6768	$235.68	$235.70	$235.70
Purchase #2	$176.69	11.276%	$196.6136	$196.61	$196.60	$196.60
Purchase #3	$215.52	11.143%	$239.5354	$239.54	$239.55	$239.50
Purchase #4	$111.66	8.610%	$121.2739	$121.27	$121.25	$121.30
Purchase #5	$40.91	3.387%	$42.2956	$42.30	$42.30	$42.30
Purchase #6	$41.76	5.230%	$43.944	$43.94	$43.95	$43.90
Purchase #7	$85.68	9.719%	$94.0072	$94.01	$94.00	$94.00
7 purchase totals =	$883.65		$973.3465	$973.35	$973.35	$973.30