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	$188.63	4.225%	$196.5996	$196.60	$196.60	$196.60
Purchase #2	$9.88	11.425%	$11.0088	$11.01	$11.00	$11.00
Purchase #3	$45.66	7.110%	$48.9064	$48.91	$48.90	$48.90
Purchase #4	$197.27	6.317%	$209.7315	$209.73	$209.75	$209.70
Purchase #5	$153.36	10.225%	$169.0411	$169.04	$169.05	$169.00
Purchase #6	$188.89	13.704%	$214.7755	$214.78	$214.80	$214.80
Purchase #7	$73.65	12.322%	$82.7252	$82.73	$82.75	$82.70
7 purchase totals =	$857.34		$932.7881	$932.80	$932.85	$932.70