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	$153.46	7.179%	$164.4769	$164.48	$164.50	$164.50
Purchase #2	$16.78	6.465%	$17.8648	$17.86	$17.85	$17.90
Purchase #3	$234.83	8.290%	$254.2974	$254.30	$254.30	$254.30
Purchase #4	$179.86	6.532%	$191.6085	$191.61	$191.60	$191.60
Purchase #5	$214.50	6.691%	$228.8522	$228.85	$228.85	$228.90
Purchase #6	$140.33	10.587%	$155.1867	$155.19	$155.20	$155.20
Purchase #7	$84.99	6.502%	$90.516	$90.52	$90.50	$90.50
7 purchase totals =	$1,024.75		$1,102.8025	$1,102.81	$1,102.80	$1,102.90