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	$189.98	3.207%	$196.0727	$196.07	$196.05	$196.10
Purchase #2	$104.33	8.518%	$113.2168	$113.22	$113.20	$113.20
Purchase #3	$95.82	10.433%	$105.8169	$105.82	$105.80	$105.80
Purchase #4	$139.98	3.268%	$144.5545	$144.55	$144.55	$144.60
Purchase #5	$215.65	9.538%	$236.2187	$236.22	$236.20	$236.20
Purchase #6	$18.54	7.670%	$19.962	$19.96	$19.95	$20.00
Purchase #7	$222.52	6.667%	$237.3554	$237.36	$237.35	$237.40
7 purchase totals =	$986.82		$1,053.1970	$1,053.20	$1,053.10	$1,053.30