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	$94.28	11.651%	$105.2646	$105.26	$105.25	$105.30
Purchase #2	$214.50	4.799%	$224.7939	$224.79	$224.80	$224.80
Purchase #3	$198.46	5.582%	$209.538	$209.54	$209.55	$209.50
Purchase #4	$49.46	8.553%	$53.6903	$53.69	$53.70	$53.70
Purchase #5	$190.39	10.228%	$209.8631	$209.86	$209.85	$209.90
Purchase #6	$94.58	8.715%	$102.8226	$102.82	$102.80	$102.80
Purchase #7	$101.75	9.464%	$111.3796	$111.38	$111.40	$111.40
7 purchase totals =	$943.42		$1,017.3521	$1,017.34	$1,017.35	$1,017.40