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	$167.25	4.483%	$174.7478	$174.75	$174.75	$174.70
Purchase #2	$217.61	4.454%	$227.3023	$227.30	$227.30	$227.30
Purchase #3	$6.49	11.793%	$7.2554	$7.26	$7.25	$7.30
Purchase #4	$156.81	12.620%	$176.5994	$176.60	$176.60	$176.60
Purchase #5	$89.75	11.339%	$99.9268	$99.93	$99.95	$99.90
Purchase #6	$36.71	12.423%	$41.2705	$41.27	$41.25	$41.30
Purchase #7	$101.27	5.158%	$106.4935	$106.49	$106.50	$106.50
7 purchase totals =	$775.89		$833.5957	$833.60	$833.60	$833.60