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	$211.57	13.862%	$240.8978	$240.90	$240.90	$240.90
Purchase #2	$20.56	9.221%	$22.4558	$22.46	$22.45	$22.50
Purchase #3	$87.82	8.777%	$95.528	$95.53	$95.55	$95.50
Purchase #4	$208.65	6.388%	$221.9786	$221.98	$222.00	$222.00
Purchase #5	$54.68	4.111%	$56.9279	$56.93	$56.95	$56.90
Purchase #6	$164.30	3.394%	$169.8763	$169.88	$169.90	$169.90
Purchase #7	$214.51	11.397%	$238.9577	$238.96	$238.95	$239.00
7 purchase totals =	$962.09		$1,046.6221	$1,046.64	$1,046.70	$1,046.70