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	$224.39	7.404%	$241.0038	$241.00	$241.00	$241.00
Purchase #2	$203.43	4.481%	$212.5457	$212.55	$212.55	$212.50
Purchase #3	$79.50	13.585%	$90.3001	$90.30	$90.30	$90.30
Purchase #4	$215.61	13.249%	$244.1762	$244.18	$244.20	$244.20
Purchase #5	$232.72	7.605%	$250.4184	$250.42	$250.40	$250.40
Purchase #6	$42.89	11.352%	$47.7589	$47.76	$47.75	$47.80
Purchase #7	$132.60	7.572%	$142.6405	$142.64	$142.65	$142.60
7 purchase totals =	$1,131.14		$1,228.8436	$1,228.85	$1,228.85	$1,228.80