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	$133.30	11.722%	$148.9254	$148.93	$148.95	$148.90
Purchase #2	$117.43	12.197%	$131.7529	$131.75	$131.75	$131.80
Purchase #3	$127.63	5.255%	$134.337	$134.34	$134.35	$134.30
Purchase #4	$53.69	13.709%	$61.0504	$61.05	$61.05	$61.10
Purchase #5	$54.73	5.259%	$57.6083	$57.61	$57.60	$57.60
Purchase #6	$248.57	12.452%	$279.5219	$279.52	$279.50	$279.50
Purchase #7	$118.56	12.126%	$132.9366	$132.94	$132.95	$132.90
7 purchase totals =	$853.91		$946.1325	$946.14	$946.15	$946.10