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	$214.60	5.234%	$225.8322	$225.83	$225.85	$225.80
Purchase #2	$113.77	4.571%	$118.9704	$118.97	$118.95	$119.00
Purchase #3	$34.66	8.640%	$37.6546	$37.65	$37.65	$37.70
Purchase #4	$37.98	3.345%	$39.2504	$39.25	$39.25	$39.30
Purchase #5	$59.95	3.441%	$62.0129	$62.01	$62.00	$62.00
Purchase #6	$152.49	12.331%	$171.2935	$171.29	$171.30	$171.30
Purchase #7	$99.63	3.269%	$102.8869	$102.89	$102.90	$102.90
7 purchase totals =	$713.08		$757.9009	$757.89	$757.90	$758.00