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	$184.42	6.365%	$196.1583	$196.16	$196.15	$196.20
Purchase #2	$107.96	7.768%	$116.3463	$116.35	$116.35	$116.30
Purchase #3	$140.96	12.360%	$158.3827	$158.38	$158.40	$158.40
Purchase #4	$76.74	7.533%	$82.5208	$82.52	$82.50	$82.50
Purchase #5	$137.59	9.622%	$150.8289	$150.83	$150.85	$150.80
Purchase #6	$214.76	12.104%	$240.7546	$240.75	$240.75	$240.80
Purchase #7	$137.57	9.282%	$150.3392	$150.34	$150.35	$150.30
7 purchase totals =	$1,000.00		$1,095.3308	$1,095.33	$1,095.35	$1,095.30