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	$126.59	4.330%	$132.0713	$132.07	$132.05	$132.10
Purchase #2	$63.47	9.321%	$69.386	$69.39	$69.40	$69.40
Purchase #3	$168.46	3.560%	$174.4572	$174.46	$174.45	$174.50
Purchase #4	$101.85	7.580%	$109.5702	$109.57	$109.55	$109.60
Purchase #5	$175.63	3.546%	$181.8578	$181.86	$181.85	$181.90
Purchase #6	$233.69	3.691%	$242.3155	$242.32	$242.30	$242.30
Purchase #7	$229.49	5.125%	$241.2514	$241.25	$241.25	$241.30
7 purchase totals =	$1,099.18		$1,150.9094	$1,150.92	$1,150.85	$1,151.10