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	$97.94	7.177%	$104.9692	$104.97	$104.95	$105.00
Purchase #2	$119.86	9.728%	$131.52	$131.52	$131.50	$131.50
Purchase #3	$234.83	3.583%	$243.244	$243.24	$243.25	$243.20
Purchase #4	$13.60	3.834%	$14.1214	$14.12	$14.10	$14.10
Purchase #5	$16.27	13.383%	$18.4474	$18.45	$18.45	$18.40
Purchase #6	$187.94	4.388%	$196.1868	$196.19	$196.20	$196.20
Purchase #7	$233.55	3.227%	$241.0867	$241.09	$241.10	$241.10
7 purchase totals =	$903.99		$949.5755	$949.58	$949.55	$949.50