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	$93.31	13.431%	$105.8425	$105.84	$105.85	$105.80
Purchase #2	$146.90	6.418%	$156.328	$156.33	$156.35	$156.30
Purchase #3	$225.59	10.674%	$249.6695	$249.67	$249.65	$249.70
Purchase #4	$173.45	5.417%	$182.8458	$182.85	$182.85	$182.80
Purchase #5	$214.72	8.254%	$232.443	$232.44	$232.45	$232.40
Purchase #6	$42.53	8.545%	$46.1642	$46.16	$46.15	$46.20
Purchase #7	$112.46	9.815%	$123.4979	$123.50	$123.50	$123.50
7 purchase totals =	$1,008.96		$1,096.7909	$1,096.79	$1,096.80	$1,096.70