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	$87.38	10.648%	$96.6842	$96.68	$96.70	$96.70
Purchase #2	$80.61	7.774%	$86.8766	$86.88	$86.90	$86.90
Purchase #3	$239.72	6.587%	$255.5104	$255.51	$255.50	$255.50
Purchase #4	$225.74	8.518%	$244.9685	$244.97	$244.95	$245.00
Purchase #5	$61.69	6.769%	$65.8658	$65.87	$65.85	$65.90
Purchase #6	$217.77	12.722%	$245.4747	$245.47	$245.45	$245.50
Purchase #7	$201.28	12.855%	$227.1545	$227.15	$227.15	$227.20
7 purchase totals =	$1,114.19		$1,222.5347	$1,222.53	$1,222.50	$1,222.70