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	$221.45	7.691%	$238.4817	$238.48	$238.50	$238.50
Purchase #2	$175.54	6.448%	$186.8588	$186.86	$186.85	$186.90
Purchase #3	$140.32	5.763%	$148.4066	$148.41	$148.40	$148.40
Purchase #4	$113.42	13.373%	$128.5877	$128.59	$128.60	$128.60
Purchase #5	$67.43	6.790%	$72.0085	$72.01	$72.00	$72.00
Purchase #6	$128.39	8.625%	$139.4636	$139.46	$139.45	$139.50
Purchase #7	$186.58	6.834%	$199.3309	$199.33	$199.35	$199.30
7 purchase totals =	$1,033.13		$1,113.1378	$1,113.14	$1,113.15	$1,113.20