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	$156.96	9.763%	$172.284	$172.28	$172.30	$172.30
Purchase #2	$58.35	7.779%	$62.889	$62.89	$62.90	$62.90
Purchase #3	$198.44	3.604%	$205.5918	$205.59	$205.60	$205.60
Purchase #4	$71.58	13.530%	$81.2648	$81.26	$81.25	$81.30
Purchase #5	$191.91	11.219%	$213.4404	$213.44	$213.45	$213.40
Purchase #6	$156.72	10.294%	$172.8528	$172.85	$172.85	$172.90
Purchase #7	$165.96	7.180%	$177.8759	$177.88	$177.90	$177.90
7 purchase totals =	$999.92		$1,086.1987	$1,086.19	$1,086.25	$1,086.30