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	$176.29	11.560%	$196.6691	$196.67	$196.65	$196.70
Purchase #2	$168.65	4.779%	$176.7098	$176.71	$176.70	$176.70
Purchase #3	$175.78	8.443%	$190.6211	$190.62	$190.60	$190.60
Purchase #4	$33.31	11.192%	$37.0381	$37.04	$37.05	$37.00
Purchase #5	$181.81	5.655%	$192.0914	$192.09	$192.10	$192.10
Purchase #6	$89.48	5.712%	$94.5911	$94.59	$94.60	$94.60
Purchase #7	$116.91	12.430%	$131.4419	$131.44	$131.45	$131.40
7 purchase totals =	$942.23		$1,019.1625	$1,019.16	$1,019.15	$1,019.10