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	$103.96	10.277%	$114.644	$114.64	$114.65	$114.60
Purchase #2	$241.55	9.487%	$264.4658	$264.47	$264.45	$264.50
Purchase #3	$41.52	9.189%	$45.3353	$45.34	$45.35	$45.30
Purchase #4	$240.97	5.361%	$253.8884	$253.89	$253.90	$253.90
Purchase #5	$246.84	13.860%	$281.052	$281.05	$281.05	$281.10
Purchase #6	$64.73	4.700%	$67.7723	$67.77	$67.75	$67.80
Purchase #7	$39.70	10.454%	$43.8502	$43.85	$43.85	$43.90
7 purchase totals =	$979.27		$1,071.0080	$1,071.01	$1,071.00	$1,071.10