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	$222.93	9.701%	$244.5564	$244.56	$244.55	$244.60
Purchase #2	$210.32	11.668%	$234.8601	$234.86	$234.85	$234.90
Purchase #3	$36.94	5.203%	$38.862	$38.86	$38.85	$38.90
Purchase #4	$81.55	12.294%	$91.5758	$91.58	$91.60	$91.60
Purchase #5	$92.55	13.266%	$104.8277	$104.83	$104.85	$104.80
Purchase #6	$159.75	8.860%	$173.9039	$173.90	$173.90	$173.90
Purchase #7	$157.36	9.473%	$172.2667	$172.27	$172.25	$172.30
7 purchase totals =	$961.40		$1,060.8526	$1,060.86	$1,060.85	$1,061.00