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	$111.41	13.412%	$126.3523	$126.35	$126.35	$126.40
Purchase #2	$15.39	7.130%	$16.4873	$16.49	$16.50	$16.50
Purchase #3	$93.79	7.264%	$100.6029	$100.60	$100.60	$100.60
Purchase #4	$164.59	8.427%	$178.46	$178.46	$178.45	$178.50
Purchase #5	$244.59	8.705%	$265.8816	$265.88	$265.90	$265.90
Purchase #6	$240.31	8.751%	$261.3395	$261.34	$261.35	$261.30
Purchase #7	$149.97	11.655%	$167.449	$167.45	$167.45	$167.40
7 purchase totals =	$1,020.05		$1,116.5726	$1,116.57	$1,116.60	$1,116.60