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	$153.50	5.236%	$161.5373	$161.54	$161.55	$161.50
Purchase #2	$222.62	11.590%	$248.4217	$248.42	$248.40	$248.40
Purchase #3	$99.74	11.791%	$111.5003	$111.50	$111.50	$111.50
Purchase #4	$224.62	5.751%	$237.5379	$237.54	$237.55	$237.50
Purchase #5	$163.46	7.331%	$175.4433	$175.44	$175.45	$175.40
Purchase #6	$98.29	6.605%	$104.7821	$104.78	$104.80	$104.80
Purchase #7	$9.26	10.629%	$10.2442	$10.24	$10.25	$10.20
7 purchase totals =	$971.49		$1,049.4668	$1,049.46	$1,049.50	$1,049.30