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	$102.56	8.485%	$111.2622	$111.26	$111.25	$111.30
Purchase #2	$243.50	6.378%	$259.0304	$259.03	$259.05	$259.00
Purchase #3	$152.69	6.398%	$162.4591	$162.46	$162.45	$162.50
Purchase #4	$245.60	11.772%	$274.512	$274.51	$274.50	$274.50
Purchase #5	$213.28	5.867%	$225.7931	$225.79	$225.80	$225.80
Purchase #6	$190.85	6.801%	$203.8297	$203.83	$203.85	$203.80
Purchase #7	$160.72	4.409%	$167.8061	$167.81	$167.80	$167.80
7 purchase totals =	$1,309.20		$1,404.6926	$1,404.69	$1,404.70	$1,404.70