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	$196.61	11.545%	$219.3086	$219.31	$219.30	$219.30
Purchase #2	$199.92	11.289%	$222.489	$222.49	$222.50	$222.50
Purchase #3	$109.49	10.226%	$120.6864	$120.69	$120.70	$120.70
Purchase #4	$17.47	10.337%	$19.2759	$19.28	$19.30	$19.30
Purchase #5	$49.38	10.840%	$54.7328	$54.73	$54.75	$54.70
Purchase #6	$137.51	3.377%	$142.1537	$142.15	$142.15	$142.20
Purchase #7	$22.34	3.639%	$23.153	$23.15	$23.15	$23.20
7 purchase totals =	$732.72		$801.7994	$801.80	$801.85	$801.90