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	$92.57	4.784%	$96.9985	$97.00	$97.00	$97.00
Purchase #2	$202.69	6.589%	$216.0452	$216.05	$216.05	$216.00
Purchase #3	$183.37	13.604%	$208.3157	$208.32	$208.30	$208.30
Purchase #4	$95.98	9.682%	$105.2728	$105.27	$105.25	$105.30
Purchase #5	$13.53	4.170%	$14.0942	$14.09	$14.10	$14.10
Purchase #6	$107.34	9.506%	$117.5437	$117.54	$117.55	$117.50
Purchase #7	$241.86	6.781%	$258.2605	$258.26	$258.25	$258.30
7 purchase totals =	$937.34		$1,016.5306	$1,016.53	$1,016.50	$1,016.50