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	$218.40	9.330%	$238.7767	$238.78	$238.80	$238.80
Purchase #2	$220.92	9.746%	$242.4509	$242.45	$242.45	$242.50
Purchase #3	$74.71	10.279%	$82.3894	$82.39	$82.40	$82.40
Purchase #4	$25.94	5.171%	$27.2814	$27.28	$27.30	$27.30
Purchase #5	$7.30	7.856%	$7.8735	$7.87	$7.85	$7.90
Purchase #6	$226.94	7.769%	$244.571	$244.57	$244.55	$244.60
Purchase #7	$200.46	7.424%	$215.3422	$215.34	$215.35	$215.30
7 purchase totals =	$974.67		$1,058.6851	$1,058.68	$1,058.70	$1,058.80