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	$193.75	8.108%	$209.4593	$209.46	$209.45	$209.50
Purchase #2	$78.29	8.778%	$85.1623	$85.16	$85.15	$85.20
Purchase #3	$195.94	7.221%	$210.0888	$210.09	$210.10	$210.10
Purchase #4	$40.87	10.618%	$45.2096	$45.21	$45.20	$45.20
Purchase #5	$121.31	9.300%	$132.5918	$132.59	$132.60	$132.60
Purchase #6	$96.28	5.197%	$101.2837	$101.28	$101.30	$101.30
Purchase #7	$214.57	9.488%	$234.9284	$234.93	$234.95	$234.90
7 purchase totals =	$941.01		$1,018.7239	$1,018.72	$1,018.75	$1,018.80