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	$94.61	9.758%	$103.842	$103.84	$103.85	$103.80
Purchase #2	$11.26	12.127%	$12.6255	$12.63	$12.65	$12.60
Purchase #3	$155.75	10.588%	$172.2408	$172.24	$172.25	$172.20
Purchase #4	$57.68	6.406%	$61.375	$61.38	$61.40	$61.40
Purchase #5	$59.65	13.172%	$67.5071	$67.51	$67.50	$67.50
Purchase #6	$238.77	12.381%	$268.3321	$268.33	$268.35	$268.30
Purchase #7	$191.32	7.160%	$205.0185	$205.02	$205.00	$205.00
7 purchase totals =	$809.04		$890.9410	$890.95	$891.00	$890.80