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	$161.49	7.711%	$173.9425	$173.94	$173.95	$173.90
Purchase #2	$65.83	12.523%	$74.0739	$74.07	$74.05	$74.10
Purchase #3	$102.72	6.507%	$109.404	$109.40	$109.40	$109.40
Purchase #4	$60.25	12.702%	$67.903	$67.90	$67.90	$67.90
Purchase #5	$227.90	7.354%	$244.6598	$244.66	$244.65	$244.70
Purchase #6	$35.81	8.309%	$38.7855	$38.79	$38.80	$38.80
Purchase #7	$151.86	11.128%	$168.759	$168.76	$168.75	$168.80
7 purchase totals =	$805.86		$877.5277	$877.52	$877.50	$877.60