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	$215.29	10.364%	$237.6027	$237.60	$237.60	$237.60
Purchase #2	$60.69	9.712%	$66.5842	$66.58	$66.60	$66.60
Purchase #3	$214.31	12.829%	$241.8038	$241.80	$241.80	$241.80
Purchase #4	$60.50	11.751%	$67.6094	$67.61	$67.60	$67.60
Purchase #5	$157.85	11.725%	$176.3579	$176.36	$176.35	$176.40
Purchase #6	$113.43	12.471%	$127.5759	$127.58	$127.60	$127.60
Purchase #7	$134.48	13.789%	$153.0234	$153.02	$153.00	$153.00
7 purchase totals =	$956.55		$1,070.5573	$1,070.55	$1,070.55	$1,070.60