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	$169.76	3.575%	$175.8289	$175.83	$175.85	$175.80
Purchase #2	$134.67	12.687%	$151.7556	$151.76	$151.75	$151.80
Purchase #3	$99.50	11.606%	$111.048	$111.05	$111.05	$111.00
Purchase #4	$44.35	12.478%	$49.884	$49.88	$49.90	$49.90
Purchase #5	$119.98	9.346%	$131.1933	$131.19	$131.20	$131.20
Purchase #6	$77.38	11.854%	$86.5526	$86.55	$86.55	$86.60
Purchase #7	$111.29	8.150%	$120.3601	$120.36	$120.35	$120.40
7 purchase totals =	$756.93		$826.6225	$826.62	$826.65	$826.70