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	$83.54	13.702%	$94.9867	$94.99	$95.00	$95.00
Purchase #2	$140.26	3.612%	$145.3262	$145.33	$145.35	$145.30
Purchase #3	$116.40	5.716%	$123.0534	$123.05	$123.05	$123.10
Purchase #4	$227.66	12.329%	$255.7282	$255.73	$255.75	$255.70
Purchase #5	$50.64	6.867%	$54.1174	$54.12	$54.10	$54.10
Purchase #6	$211.83	6.638%	$225.8913	$225.89	$225.90	$225.90
Purchase #7	$215.43	4.793%	$225.7556	$225.76	$225.75	$225.80
7 purchase totals =	$1,045.76		$1,124.8588	$1,124.87	$1,124.90	$1,124.90