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	$183.82	7.629%	$197.8436	$197.84	$197.85	$197.80
Purchase #2	$40.87	6.478%	$43.5176	$43.52	$43.50	$43.50
Purchase #3	$96.82	3.865%	$100.5621	$100.56	$100.55	$100.60
Purchase #4	$110.53	13.149%	$125.0636	$125.06	$125.05	$125.10
Purchase #5	$121.85	7.619%	$131.1338	$131.13	$131.15	$131.10
Purchase #6	$175.69	13.544%	$199.4855	$199.49	$199.50	$199.50
Purchase #7	$80.31	5.853%	$85.0105	$85.01	$85.00	$85.00
7 purchase totals =	$809.89		$882.6167	$882.61	$882.60	$882.60