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	$196.39	4.706%	$205.6321	$205.63	$205.65	$205.60
Purchase #2	$138.58	9.391%	$151.594	$151.59	$151.60	$151.60
Purchase #3	$124.60	9.416%	$136.3323	$136.33	$136.35	$136.30
Purchase #4	$72.37	6.659%	$77.1891	$77.19	$77.20	$77.20
Purchase #5	$97.38	6.653%	$103.8587	$103.86	$103.85	$103.90
Purchase #6	$62.26	7.674%	$67.0378	$67.04	$67.05	$67.00
Purchase #7	$128.56	4.439%	$134.2668	$134.27	$134.25	$134.30
7 purchase totals =	$820.14		$875.9108	$875.91	$875.95	$875.90