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	$61.93	11.308%	$68.933	$68.93	$68.95	$68.90
Purchase #2	$20.95	11.824%	$23.4271	$23.43	$23.45	$23.40
Purchase #3	$55.49	6.620%	$59.1634	$59.16	$59.15	$59.20
Purchase #4	$89.69	5.268%	$94.4149	$94.41	$94.40	$94.40
Purchase #5	$16.61	11.122%	$18.4574	$18.46	$18.45	$18.50
Purchase #6	$31.47	9.374%	$34.42	$34.42	$34.40	$34.40
Purchase #7	$130.69	4.514%	$136.5893	$136.59	$136.60	$136.60
7 purchase totals =	$406.83		$435.4051	$435.40	$435.40	$435.40