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	$208.40	6.652%	$222.2628	$222.26	$222.25	$222.30
Purchase #2	$12.46	11.478%	$13.8902	$13.89	$13.90	$13.90
Purchase #3	$80.76	13.141%	$91.3727	$91.37	$91.35	$91.40
Purchase #4	$250.91	9.410%	$274.5206	$274.52	$274.50	$274.50
Purchase #5	$37.51	8.282%	$40.6166	$40.62	$40.60	$40.60
Purchase #6	$52.79	13.357%	$59.8412	$59.84	$59.85	$59.80
Purchase #7	$61.59	3.469%	$63.7266	$63.73	$63.75	$63.70
7 purchase totals =	$704.42		$766.2307	$766.23	$766.20	$766.20