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	$108.33	3.356%	$111.9656	$111.97	$111.95	$112.00
Purchase #2	$87.36	8.253%	$94.5698	$94.57	$94.55	$94.60
Purchase #3	$65.55	8.503%	$71.1237	$71.12	$71.10	$71.10
Purchase #4	$153.45	7.130%	$164.391	$164.39	$164.40	$164.40
Purchase #5	$151.39	9.104%	$165.1725	$165.17	$165.15	$165.20
Purchase #6	$154.89	8.622%	$168.2446	$168.24	$168.25	$168.20
Purchase #7	$241.43	7.443%	$259.3996	$259.40	$259.40	$259.40
7 purchase totals =	$962.40		$1,034.8668	$1,034.86	$1,034.80	$1,034.90