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	$161.44	4.415%	$168.5676	$168.57	$168.55	$168.60
Purchase #2	$105.79	12.567%	$119.0846	$119.08	$119.10	$119.10
Purchase #3	$137.54	8.184%	$148.7963	$148.80	$148.80	$148.80
Purchase #4	$48.73	11.392%	$54.2813	$54.28	$54.30	$54.30
Purchase #5	$128.44	6.326%	$136.5651	$136.57	$136.55	$136.60
Purchase #6	$230.72	12.376%	$259.2739	$259.27	$259.25	$259.30
Purchase #7	$121.47	4.765%	$127.258	$127.26	$127.25	$127.30
7 purchase totals =	$934.13		$1,013.8268	$1,013.83	$1,013.80	$1,014.00