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	$114.47	11.541%	$127.681	$127.68	$127.70	$127.70
Purchase #2	$129.56	6.242%	$137.6471	$137.65	$137.65	$137.60
Purchase #3	$143.31	11.288%	$159.4868	$159.49	$159.50	$159.50
Purchase #4	$210.98	8.153%	$228.1812	$228.18	$228.20	$228.20
Purchase #5	$248.30	9.665%	$272.2982	$272.30	$272.30	$272.30
Purchase #6	$11.67	13.786%	$13.2788	$13.28	$13.30	$13.30
Purchase #7	$71.71	9.593%	$78.5891	$78.59	$78.60	$78.60
7 purchase totals =	$930.00		$1,017.1622	$1,017.17	$1,017.25	$1,017.20