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	$146.83	7.732%	$158.1829	$158.18	$158.20	$158.20
Purchase #2	$59.62	5.604%	$62.9611	$62.96	$62.95	$63.00
Purchase #3	$177.41	10.676%	$196.3503	$196.35	$196.35	$196.40
Purchase #4	$132.77	13.102%	$150.1655	$150.17	$150.15	$150.20
Purchase #5	$168.85	3.799%	$175.2646	$175.26	$175.25	$175.30
Purchase #6	$131.67	11.384%	$146.6593	$146.66	$146.65	$146.70
Purchase #7	$140.94	4.546%	$147.3471	$147.35	$147.35	$147.30
7 purchase totals =	$958.09		$1,036.9308	$1,036.93	$1,036.90	$1,037.10