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	$115.68	10.425%	$127.7396	$127.74	$127.75	$127.70
Purchase #2	$156.48	10.340%	$172.66	$172.66	$172.65	$172.70
Purchase #3	$226.56	3.647%	$234.8226	$234.82	$234.80	$234.80
Purchase #4	$198.79	5.202%	$209.1311	$209.13	$209.15	$209.10
Purchase #5	$97.66	8.106%	$105.5763	$105.58	$105.60	$105.60
Purchase #6	$71.46	4.552%	$74.7129	$74.71	$74.70	$74.70
Purchase #7	$81.34	12.477%	$91.4888	$91.49	$91.50	$91.50
7 purchase totals =	$947.97		$1,016.1313	$1,016.13	$1,016.15	$1,016.10