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	$215.63	8.444%	$233.8378	$233.84	$233.85	$233.80
Purchase #2	$220.91	10.813%	$244.797	$244.80	$244.80	$244.80
Purchase #3	$185.36	8.570%	$201.2454	$201.25	$201.25	$201.20
Purchase #4	$55.92	9.389%	$61.1703	$61.17	$61.15	$61.20
Purchase #5	$120.43	6.328%	$128.0508	$128.05	$128.05	$128.10
Purchase #6	$112.72	4.253%	$117.514	$117.51	$117.50	$117.50
Purchase #7	$31.40	4.842%	$32.9204	$32.92	$32.90	$32.90
7 purchase totals =	$942.37		$1,019.5357	$1,019.54	$1,019.50	$1,019.50