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	$94.93	9.398%	$103.8515	$103.85	$103.85	$103.90
Purchase #2	$16.27	6.162%	$17.2726	$17.27	$17.25	$17.30
Purchase #3	$133.37	10.731%	$147.6819	$147.68	$147.70	$147.70
Purchase #4	$42.91	5.535%	$45.2851	$45.29	$45.30	$45.30
Purchase #5	$245.30	11.231%	$272.8496	$272.85	$272.85	$272.80
Purchase #6	$155.53	4.192%	$162.0498	$162.05	$162.05	$162.00
Purchase #7	$180.73	8.874%	$196.768	$196.77	$196.75	$196.80
7 purchase totals =	$869.04		$945.7585	$945.76	$945.75	$945.80