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	$135.29	5.375%	$142.5618	$142.56	$142.55	$142.60
Purchase #2	$135.29	4.801%	$141.7853	$141.79	$141.80	$141.80
Purchase #3	$57.57	3.305%	$59.4727	$59.47	$59.45	$59.50
Purchase #4	$162.60	4.449%	$169.8341	$169.83	$169.85	$169.80
Purchase #5	$171.80	6.287%	$182.6011	$182.60	$182.60	$182.60
Purchase #6	$250.62	8.207%	$271.1884	$271.19	$271.20	$271.20
Purchase #7	$46.40	4.649%	$48.5571	$48.56	$48.55	$48.60
7 purchase totals =	$959.57		$1,016.0005	$1,016.00	$1,016.00	$1,016.10