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	$41.38	12.373%	$46.4999	$46.50	$46.50	$46.50
Purchase #2	$171.87	7.421%	$184.6245	$184.62	$184.60	$184.60
Purchase #3	$79.57	5.349%	$83.8262	$83.83	$83.85	$83.80
Purchase #4	$212.59	6.678%	$226.7868	$226.79	$226.80	$226.80
Purchase #5	$74.29	5.457%	$78.344	$78.34	$78.35	$78.30
Purchase #6	$146.69	10.710%	$162.4005	$162.40	$162.40	$162.40
Purchase #7	$240.62	12.651%	$271.0608	$271.06	$271.05	$271.10
7 purchase totals =	$967.01		$1,053.5427	$1,053.54	$1,053.55	$1,053.50