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	$85.48	11.733%	$95.5094	$95.51	$95.50	$95.50
Purchase #2	$152.60	9.291%	$166.7781	$166.78	$166.80	$166.80
Purchase #3	$126.36	4.283%	$131.772	$131.77	$131.75	$131.80
Purchase #4	$67.87	11.411%	$75.6146	$75.61	$75.60	$75.60
Purchase #5	$178.56	9.809%	$196.075	$196.08	$196.10	$196.10
Purchase #6	$68.44	12.713%	$77.1408	$77.14	$77.15	$77.10
Purchase #7	$186.25	13.477%	$211.3509	$211.35	$211.35	$211.40
7 purchase totals =	$865.56		$954.2408	$954.24	$954.25	$954.30