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	$173.87	12.749%	$196.0367	$196.04	$196.05	$196.00
Purchase #2	$83.31	10.296%	$91.8876	$91.89	$91.90	$91.90
Purchase #3	$164.65	13.478%	$186.8415	$186.84	$186.85	$186.80
Purchase #4	$134.89	3.166%	$139.1606	$139.16	$139.15	$139.20
Purchase #5	$241.82	8.603%	$262.6238	$262.62	$262.60	$262.60
Purchase #6	$213.36	11.618%	$238.1482	$238.15	$238.15	$238.10
Purchase #7	$186.29	11.681%	$208.0505	$208.05	$208.05	$208.10
7 purchase totals =	$1,198.19		$1,322.7489	$1,322.75	$1,322.75	$1,322.70