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	$125.55	5.589%	$132.567	$132.57	$132.55	$132.60
Purchase #2	$43.42	4.668%	$45.4468	$45.45	$45.45	$45.40
Purchase #3	$221.60	10.310%	$244.447	$244.45	$244.45	$244.40
Purchase #4	$157.78	10.220%	$173.9051	$173.91	$173.90	$173.90
Purchase #5	$27.73	6.488%	$29.5291	$29.53	$29.55	$29.50
Purchase #6	$196.38	6.669%	$209.4766	$209.48	$209.50	$209.50
Purchase #7	$41.79	11.392%	$46.5507	$46.55	$46.55	$46.60
7 purchase totals =	$814.25		$881.9223	$881.94	$881.95	$881.90