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	$218.26	12.465%	$245.4661	$245.47	$245.45	$245.50
Purchase #2	$82.68	8.667%	$89.8459	$89.85	$89.85	$89.80
Purchase #3	$5.71	11.196%	$6.3493	$6.35	$6.35	$6.30
Purchase #4	$111.35	3.431%	$115.1704	$115.17	$115.15	$115.20
Purchase #5	$232.50	11.117%	$258.347	$258.35	$258.35	$258.30
Purchase #6	$173.68	9.663%	$190.4627	$190.46	$190.45	$190.50
Purchase #7	$159.75	12.262%	$179.3385	$179.34	$179.35	$179.30
7 purchase totals =	$983.93		$1,084.9799	$1,084.99	$1,084.95	$1,084.90