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	$33.33	8.513%	$36.1674	$36.17	$36.15	$36.20
Purchase #2	$41.90	3.689%	$43.4457	$43.45	$43.45	$43.40
Purchase #3	$84.85	12.203%	$95.2042	$95.20	$95.20	$95.20
Purchase #4	$84.30	13.869%	$95.9916	$95.99	$96.00	$96.00
Purchase #5	$185.87	5.838%	$196.7211	$196.72	$196.70	$196.70
Purchase #6	$154.50	12.834%	$174.3285	$174.33	$174.35	$174.30
Purchase #7	$125.97	4.341%	$131.4384	$131.44	$131.45	$131.40
7 purchase totals =	$710.72		$773.2969	$773.30	$773.30	$773.20