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	$108.30	5.444%	$114.1959	$114.20	$114.20	$114.20
Purchase #2	$162.46	11.856%	$181.7213	$181.72	$181.70	$181.70
Purchase #3	$157.94	4.773%	$165.4785	$165.48	$165.50	$165.50
Purchase #4	$195.74	8.428%	$212.237	$212.24	$212.25	$212.20
Purchase #5	$167.77	12.351%	$188.4913	$188.49	$188.50	$188.50
Purchase #6	$89.86	12.170%	$100.796	$100.80	$100.80	$100.80
Purchase #7	$93.34	12.332%	$104.8507	$104.85	$104.85	$104.90
7 purchase totals =	$975.41		$1,067.7707	$1,067.78	$1,067.80	$1,067.80