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	$152.30	11.394%	$169.6531	$169.65	$169.65	$169.70
Purchase #2	$200.86	10.650%	$222.2516	$222.25	$222.25	$222.30
Purchase #3	$30.47	13.480%	$34.5774	$34.58	$34.60	$34.60
Purchase #4	$93.35	6.430%	$99.3524	$99.35	$99.35	$99.40
Purchase #5	$155.82	12.249%	$174.9064	$174.91	$174.90	$174.90
Purchase #6	$123.36	10.649%	$136.4966	$136.50	$136.50	$136.50
Purchase #7	$98.87	13.821%	$112.5348	$112.53	$112.55	$112.50
7 purchase totals =	$855.03		$949.7723	$949.77	$949.80	$949.90