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	$68.44	4.510%	$71.5266	$71.53	$71.55	$71.50
Purchase #2	$76.70	11.130%	$85.2367	$85.24	$85.25	$85.20
Purchase #3	$85.58	11.541%	$95.4568	$95.46	$95.45	$95.50
Purchase #4	$170.81	10.712%	$189.1072	$189.11	$189.10	$189.10
Purchase #5	$220.30	3.171%	$227.2857	$227.29	$227.30	$227.30
Purchase #6	$198.82	5.672%	$210.0971	$210.10	$210.10	$210.10
Purchase #7	$217.64	9.750%	$238.8599	$238.86	$238.85	$238.90
7 purchase totals =	$1,038.29		$1,117.5700	$1,117.59	$1,117.60	$1,117.60