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	$150.57	7.762%	$162.2572	$162.26	$162.25	$162.30
Purchase #2	$218.38	3.163%	$225.2874	$225.29	$225.30	$225.30
Purchase #3	$206.73	12.795%	$233.1811	$233.18	$233.20	$233.20
Purchase #4	$32.42	8.838%	$35.2853	$35.29	$35.30	$35.30
Purchase #5	$155.88	11.593%	$173.9512	$173.95	$173.95	$174.00
Purchase #6	$139.51	11.517%	$155.5774	$155.58	$155.60	$155.60
Purchase #7	$105.52	6.498%	$112.3767	$112.38	$112.40	$112.40
7 purchase totals =	$1,009.01		$1,097.9163	$1,097.93	$1,098.00	$1,098.10