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	$184.30	13.776%	$209.6892	$209.69	$209.70	$209.70
Purchase #2	$236.61	10.712%	$261.9557	$261.96	$261.95	$262.00
Purchase #3	$56.46	9.751%	$61.9654	$61.97	$61.95	$62.00
Purchase #4	$180.80	10.853%	$200.4222	$200.42	$200.40	$200.40
Purchase #5	$165.88	11.741%	$185.356	$185.36	$185.35	$185.40
Purchase #6	$149.43	13.149%	$169.0786	$169.08	$169.10	$169.10
Purchase #7	$227.46	12.769%	$256.5044	$256.50	$256.50	$256.50
7 purchase totals =	$1,200.94		$1,344.9715	$1,344.98	$1,344.95	$1,345.10