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	$137.52	10.550%	$152.0284	$152.03	$152.05	$152.00
Purchase #2	$62.52	5.461%	$65.9342	$65.93	$65.95	$65.90
Purchase #3	$89.35	7.593%	$96.1343	$96.13	$96.15	$96.10
Purchase #4	$232.50	11.831%	$260.0071	$260.01	$260.00	$260.00
Purchase #5	$105.63	11.221%	$117.4827	$117.48	$117.50	$117.50
Purchase #6	$174.44	9.763%	$191.4706	$191.47	$191.45	$191.50
Purchase #7	$157.66	3.289%	$162.8454	$162.85	$162.85	$162.80
7 purchase totals =	$959.62		$1,045.9027	$1,045.90	$1,045.95	$1,045.80