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	$152.69	12.190%	$171.3029	$171.30	$171.30	$171.30
Purchase #2	$114.52	4.235%	$119.3699	$119.37	$119.35	$119.40
Purchase #3	$99.61	10.140%	$109.7105	$109.71	$109.70	$109.70
Purchase #4	$51.25	10.482%	$56.622	$56.62	$56.60	$56.60
Purchase #5	$215.53	13.436%	$244.4886	$244.49	$244.50	$244.50
Purchase #6	$119.70	3.398%	$123.7674	$123.77	$123.75	$123.80
Purchase #7	$213.49	3.126%	$220.1637	$220.16	$220.15	$220.20
7 purchase totals =	$966.79		$1,045.4250	$1,045.42	$1,045.35	$1,045.50