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	$85.69	7.633%	$92.2307	$92.23	$92.25	$92.20
Purchase #2	$20.93	7.104%	$22.4169	$22.42	$22.40	$22.40
Purchase #3	$51.51	6.492%	$54.854	$54.85	$54.85	$54.90
Purchase #4	$12.73	13.391%	$14.4347	$14.43	$14.45	$14.40
Purchase #5	$99.53	12.490%	$111.9613	$111.96	$111.95	$112.00
Purchase #6	$16.92	11.165%	$18.8091	$18.81	$18.80	$18.80
Purchase #7	$84.75	3.284%	$87.5332	$87.53	$87.55	$87.50
7 purchase totals =	$372.06		$402.2399	$402.23	$402.25	$402.20