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	$190.30	11.548%	$212.2758	$212.28	$212.30	$212.30
Purchase #2	$6.86	3.492%	$7.0996	$7.10	$7.10	$7.10
Purchase #3	$189.42	7.873%	$204.333	$204.33	$204.35	$204.30
Purchase #4	$99.87	11.743%	$111.5977	$111.60	$111.60	$111.60
Purchase #5	$102.67	13.558%	$116.59	$116.59	$116.60	$116.60
Purchase #6	$131.46	7.722%	$141.6113	$141.61	$141.60	$141.60
Purchase #7	$236.26	9.499%	$258.7023	$258.70	$258.70	$258.70
7 purchase totals =	$956.84		$1,052.2097	$1,052.21	$1,052.25	$1,052.20