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	$111.67	12.254%	$125.354	$125.35	$125.35	$125.40
Purchase #2	$188.28	10.678%	$208.3845	$208.38	$208.40	$208.40
Purchase #3	$101.72	7.530%	$109.3795	$109.38	$109.40	$109.40
Purchase #4	$57.60	10.123%	$63.4308	$63.43	$63.45	$63.40
Purchase #5	$166.47	10.121%	$183.3184	$183.32	$183.30	$183.30
Purchase #6	$249.68	4.663%	$261.3226	$261.32	$261.30	$261.30
Purchase #7	$91.47	13.185%	$103.5303	$103.53	$103.55	$103.50
7 purchase totals =	$966.89		$1,054.7201	$1,054.71	$1,054.75	$1,054.70