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	$190.30	3.138%	$196.2716	$196.27	$196.25	$196.30
Purchase #2	$188.85	4.184%	$196.7515	$196.75	$196.75	$196.80
Purchase #3	$119.48	3.552%	$123.7239	$123.72	$123.70	$123.70
Purchase #4	$89.77	12.394%	$100.8961	$100.90	$100.90	$100.90
Purchase #5	$109.80	7.834%	$118.4017	$118.40	$118.40	$118.40
Purchase #6	$87.95	3.588%	$91.1056	$91.11	$91.10	$91.10
Purchase #7	$122.39	10.308%	$135.006	$135.01	$135.00	$135.00
7 purchase totals =	$908.54		$962.1564	$962.16	$962.10	$962.20