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	$182.74	7.578%	$196.588	$196.59	$196.60	$196.60
Purchase #2	$222.60	6.739%	$237.601	$237.60	$237.60	$237.60
Purchase #3	$184.25	8.721%	$200.3184	$200.32	$200.30	$200.30
Purchase #4	$82.65	4.480%	$86.3527	$86.35	$86.35	$86.40
Purchase #5	$190.78	6.762%	$203.6805	$203.68	$203.70	$203.70
Purchase #6	$151.57	7.183%	$162.4573	$162.46	$162.45	$162.50
Purchase #7	$109.71	11.863%	$122.7249	$122.72	$122.70	$122.70
7 purchase totals =	$1,124.30		$1,209.7228	$1,209.72	$1,209.70	$1,209.80