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	$196.82	4.317%	$205.3167	$205.32	$205.30	$205.30
Purchase #2	$218.83	3.551%	$226.6007	$226.60	$226.60	$226.60
Purchase #3	$96.40	4.206%	$100.4546	$100.45	$100.45	$100.50
Purchase #4	$210.45	8.507%	$228.353	$228.35	$228.35	$228.40
Purchase #5	$175.88	11.578%	$196.2434	$196.24	$196.25	$196.20
Purchase #6	$61.94	5.793%	$65.5282	$65.53	$65.55	$65.50
Purchase #7	$189.70	10.873%	$210.3261	$210.33	$210.35	$210.30
7 purchase totals =	$1,150.02		$1,232.8227	$1,232.82	$1,232.85	$1,232.80