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	$196.97	11.291%	$219.2099	$219.21	$219.20	$219.20
Purchase #2	$146.53	13.506%	$166.3203	$166.32	$166.30	$166.30
Purchase #3	$58.75	8.799%	$63.9194	$63.92	$63.90	$63.90
Purchase #4	$142.80	8.502%	$154.9409	$154.94	$154.95	$154.90
Purchase #5	$14.37	3.378%	$14.8554	$14.86	$14.85	$14.90
Purchase #6	$203.90	10.287%	$224.8752	$224.88	$224.90	$224.90
Purchase #7	$162.92	5.518%	$171.9099	$171.91	$171.90	$171.90
7 purchase totals =	$926.24		$1,016.0310	$1,016.04	$1,016.00	$1,016.00