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	$114.25	10.123%	$125.8155	$125.82	$125.80	$125.80
Purchase #2	$94.42	6.803%	$100.8434	$100.84	$100.85	$100.80
Purchase #3	$179.51	4.673%	$187.8985	$187.90	$187.90	$187.90
Purchase #4	$217.46	7.350%	$233.4433	$233.44	$233.45	$233.40
Purchase #5	$107.94	12.596%	$121.5361	$121.54	$121.55	$121.50
Purchase #6	$190.51	13.703%	$216.6156	$216.62	$216.60	$216.60
Purchase #7	$114.49	4.221%	$119.3226	$119.32	$119.30	$119.30
7 purchase totals =	$1,018.58		$1,105.4750	$1,105.48	$1,105.45	$1,105.30