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	$212.26	11.473%	$236.6126	$236.61	$236.60	$236.60
Purchase #2	$190.26	10.786%	$210.7814	$210.78	$210.80	$210.80
Purchase #3	$13.86	7.551%	$14.9066	$14.91	$14.90	$14.90
Purchase #4	$80.29	3.851%	$83.382	$83.38	$83.40	$83.40
Purchase #5	$175.76	8.384%	$190.4957	$190.50	$190.50	$190.50
Purchase #6	$218.93	7.528%	$235.4111	$235.41	$235.40	$235.40
Purchase #7	$92.38	7.747%	$99.5367	$99.54	$99.55	$99.50
7 purchase totals =	$983.74		$1,071.1261	$1,071.13	$1,071.15	$1,071.10