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	$106.66	9.263%	$116.5399	$116.54	$116.55	$116.50
Purchase #2	$195.31	6.475%	$207.9563	$207.96	$207.95	$208.00
Purchase #3	$249.34	9.409%	$272.8004	$272.80	$272.80	$272.80
Purchase #4	$86.33	10.860%	$95.7054	$95.71	$95.70	$95.70
Purchase #5	$12.96	11.498%	$14.4501	$14.45	$14.45	$14.50
Purchase #6	$90.80	10.793%	$100.6	$100.60	$100.60	$100.60
Purchase #7	$205.82	13.289%	$233.1714	$233.17	$233.15	$233.20
7 purchase totals =	$947.22		$1,041.2235	$1,041.23	$1,041.20	$1,041.30