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	$184.47	8.238%	$199.6666	$199.67	$199.65	$199.70
Purchase #2	$97.84	13.617%	$111.1629	$111.16	$111.15	$111.20
Purchase #3	$21.96	13.265%	$24.873	$24.87	$24.85	$24.90
Purchase #4	$153.47	8.240%	$166.1159	$166.12	$166.10	$166.10
Purchase #5	$164.61	4.582%	$172.1524	$172.15	$172.15	$172.20
Purchase #6	$225.45	13.413%	$255.6896	$255.69	$255.70	$255.70
Purchase #7	$153.38	6.183%	$162.8635	$162.86	$162.85	$162.90
7 purchase totals =	$1,001.18		$1,092.5239	$1,092.52	$1,092.45	$1,092.70