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	$219.31	7.611%	$236.0017	$236.00	$236.00	$236.00
Purchase #2	$237.93	13.870%	$270.9309	$270.93	$270.95	$270.90
Purchase #3	$39.25	7.405%	$42.1565	$42.16	$42.15	$42.20
Purchase #4	$150.43	7.441%	$161.6235	$161.62	$161.60	$161.60
Purchase #5	$157.76	10.666%	$174.5867	$174.59	$174.60	$174.60
Purchase #6	$91.47	9.197%	$99.8825	$99.88	$99.90	$99.90
Purchase #7	$140.59	7.630%	$151.317	$151.32	$151.30	$151.30
7 purchase totals =	$1,036.74		$1,136.4988	$1,136.50	$1,136.50	$1,136.50