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	$119.35	12.232%	$133.9489	$133.95	$133.95	$133.90
Purchase #2	$31.25	8.363%	$33.8634	$33.86	$33.85	$33.90
Purchase #3	$145.43	4.562%	$152.0645	$152.06	$152.05	$152.10
Purchase #4	$203.98	7.429%	$219.1337	$219.13	$219.15	$219.10
Purchase #5	$75.38	8.410%	$81.7195	$81.72	$81.70	$81.70
Purchase #6	$247.42	3.476%	$256.0203	$256.02	$256.00	$256.00
Purchase #7	$116.52	12.628%	$131.2341	$131.23	$131.25	$131.20
7 purchase totals =	$939.33		$1,007.9844	$1,007.97	$1,007.95	$1,007.90