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	$212.40	13.169%	$240.371	$240.37	$240.35	$240.40
Purchase #2	$174.38	12.724%	$196.5681	$196.57	$196.55	$196.60
Purchase #3	$139.26	12.526%	$156.7037	$156.70	$156.70	$156.70
Purchase #4	$41.93	6.195%	$44.5276	$44.53	$44.55	$44.50
Purchase #5	$115.56	3.480%	$119.5815	$119.58	$119.60	$119.60
Purchase #6	$199.32	11.135%	$221.5143	$221.51	$221.50	$221.50
Purchase #7	$61.48	6.198%	$65.2905	$65.29	$65.30	$65.30
7 purchase totals =	$944.33		$1,044.5567	$1,044.55	$1,044.55	$1,044.60