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	$104.43	11.413%	$116.3486	$116.35	$116.35	$116.30
Purchase #2	$248.66	11.689%	$277.7259	$277.73	$277.75	$277.70
Purchase #3	$200.51	3.850%	$208.2296	$208.23	$208.25	$208.20
Purchase #4	$43.68	3.274%	$45.1101	$45.11	$45.10	$45.10
Purchase #5	$59.57	10.620%	$65.8963	$65.90	$65.90	$65.90
Purchase #6	$91.51	10.214%	$100.8568	$100.86	$100.85	$100.90
Purchase #7	$208.28	6.844%	$222.5347	$222.53	$222.55	$222.50
7 purchase totals =	$956.64		$1,036.7020	$1,036.71	$1,036.75	$1,036.60