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	$207.85	9.464%	$227.5209	$227.52	$227.50	$227.50
Purchase #2	$188.94	10.201%	$208.2138	$208.21	$208.20	$208.20
Purchase #3	$113.98	4.250%	$118.8242	$118.82	$118.80	$118.80
Purchase #4	$96.37	6.236%	$102.3796	$102.38	$102.40	$102.40
Purchase #5	$155.72	4.581%	$162.8535	$162.85	$162.85	$162.90
Purchase #6	$62.56	8.238%	$67.7137	$67.71	$67.70	$67.70
Purchase #7	$113.59	8.869%	$123.6643	$123.66	$123.65	$123.70
7 purchase totals =	$939.01		$1,011.1700	$1,011.15	$1,011.10	$1,011.20