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	$209.61	3.602%	$217.1602	$217.16	$217.15	$217.20
Purchase #2	$191.72	8.560%	$208.1312	$208.13	$208.15	$208.10
Purchase #3	$80.38	6.150%	$85.3234	$85.32	$85.30	$85.30
Purchase #4	$245.50	10.676%	$271.7096	$271.71	$271.70	$271.70
Purchase #5	$85.25	11.239%	$94.8312	$94.83	$94.85	$94.80
Purchase #6	$190.41	12.254%	$213.7428	$213.74	$213.75	$213.70
Purchase #7	$62.47	3.181%	$64.4572	$64.46	$64.45	$64.50
7 purchase totals =	$1,065.34		$1,155.3556	$1,155.35	$1,155.35	$1,155.30