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	$198.71	11.314%	$221.192	$221.19	$221.20	$221.20
Purchase #2	$200.31	9.380%	$219.0991	$219.10	$219.10	$219.10
Purchase #3	$38.69	12.650%	$43.5843	$43.58	$43.60	$43.60
Purchase #4	$181.62	4.733%	$190.2161	$190.22	$190.20	$190.20
Purchase #5	$219.60	13.104%	$248.3764	$248.38	$248.40	$248.40
Purchase #6	$7.52	11.557%	$8.3891	$8.39	$8.40	$8.40
Purchase #7	$110.48	5.417%	$116.4647	$116.46	$116.45	$116.50
7 purchase totals =	$956.93		$1,047.3217	$1,047.32	$1,047.35	$1,047.40