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	$119.75	11.328%	$133.3153	$133.32	$133.30	$133.30
Purchase #2	$163.68	5.592%	$172.833	$172.83	$172.85	$172.80
Purchase #3	$201.37	3.755%	$208.9314	$208.93	$208.95	$208.90
Purchase #4	$225.72	5.464%	$238.0533	$238.05	$238.05	$238.10
Purchase #5	$185.76	7.638%	$199.9483	$199.95	$199.95	$199.90
Purchase #6	$190.96	3.131%	$196.939	$196.94	$196.95	$196.90
Purchase #7	$200.46	8.398%	$217.2946	$217.29	$217.30	$217.30
7 purchase totals =	$1,287.70		$1,367.3149	$1,367.31	$1,367.35	$1,367.20