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	$213.50	11.815%	$238.725	$238.73	$238.75	$238.70
Purchase #2	$16.58	10.432%	$18.3096	$18.31	$18.30	$18.30
Purchase #3	$248.76	12.567%	$280.0217	$280.02	$280.00	$280.00
Purchase #4	$27.50	3.552%	$28.4768	$28.48	$28.50	$28.50
Purchase #5	$169.78	9.207%	$185.4116	$185.41	$185.40	$185.40
Purchase #6	$136.28	7.838%	$146.9616	$146.96	$146.95	$147.00
Purchase #7	$137.83	9.626%	$151.0975	$151.10	$151.10	$151.10
7 purchase totals =	$950.23		$1,049.0038	$1,049.01	$1,049.00	$1,049.00