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	$132.77	7.348%	$142.5259	$142.53	$142.55	$142.50
Purchase #2	$78.91	6.282%	$83.8671	$83.87	$83.85	$83.90
Purchase #3	$153.48	8.324%	$166.2557	$166.26	$166.25	$166.30
Purchase #4	$77.95	5.564%	$82.2871	$82.29	$82.30	$82.30
Purchase #5	$244.30	4.806%	$256.0411	$256.04	$256.05	$256.00
Purchase #6	$171.54	8.764%	$186.5738	$186.57	$186.55	$186.60
Purchase #7	$79.68	8.507%	$86.4584	$86.46	$86.45	$86.50
7 purchase totals =	$938.63		$1,004.0091	$1,004.02	$1,004.00	$1,004.10