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	$162.32	11.622%	$181.1848	$181.18	$181.20	$181.20
Purchase #2	$144.43	7.189%	$154.8131	$154.81	$154.80	$154.80
Purchase #3	$147.33	5.126%	$154.8821	$154.88	$154.90	$154.90
Purchase #4	$60.35	13.513%	$68.5051	$68.51	$68.50	$68.50
Purchase #5	$213.94	12.762%	$241.243	$241.24	$241.25	$241.20
Purchase #6	$211.38	12.802%	$238.4409	$238.44	$238.45	$238.40
Purchase #7	$21.83	3.732%	$22.6447	$22.64	$22.65	$22.60
7 purchase totals =	$961.58		$1,061.7137	$1,061.70	$1,061.75	$1,061.60