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	$63.26	8.522%	$68.651	$68.65	$68.65	$68.70
Purchase #2	$219.59	10.235%	$242.065	$242.07	$242.05	$242.10
Purchase #3	$86.76	4.442%	$90.6139	$90.61	$90.60	$90.60
Purchase #4	$102.97	8.571%	$111.7956	$111.80	$111.80	$111.80
Purchase #5	$142.35	10.870%	$157.8234	$157.82	$157.80	$157.80
Purchase #6	$250.51	3.732%	$259.859	$259.86	$259.85	$259.90
Purchase #7	$239.38	10.419%	$264.321	$264.32	$264.30	$264.30
7 purchase totals =	$1,104.82		$1,195.1289	$1,195.13	$1,195.05	$1,195.20