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	$224.67	9.656%	$246.3641	$246.36	$246.35	$246.40
Purchase #2	$44.76	12.844%	$50.509	$50.51	$50.50	$50.50
Purchase #3	$97.80	11.575%	$109.1204	$109.12	$109.10	$109.10
Purchase #4	$82.69	8.269%	$89.5276	$89.53	$89.55	$89.50
Purchase #5	$142.65	10.231%	$157.2445	$157.24	$157.25	$157.20
Purchase #6	$145.76	5.816%	$154.2374	$154.24	$154.25	$154.20
Purchase #7	$190.86	12.839%	$215.3645	$215.36	$215.35	$215.40
7 purchase totals =	$929.19		$1,022.3675	$1,022.36	$1,022.35	$1,022.30