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	$198.72	8.620%	$215.8497	$215.85	$215.85	$215.80
Purchase #2	$40.57	5.270%	$42.708	$42.71	$42.70	$42.70
Purchase #3	$210.69	3.482%	$218.0262	$218.03	$218.05	$218.00
Purchase #4	$160.60	12.474%	$180.6332	$180.63	$180.65	$180.60
Purchase #5	$13.69	6.352%	$14.5596	$14.56	$14.55	$14.60
Purchase #6	$99.55	12.316%	$111.8106	$111.81	$111.80	$111.80
Purchase #7	$184.33	3.444%	$190.6783	$190.68	$190.70	$190.70
7 purchase totals =	$908.15		$974.2656	$974.27	$974.30	$974.20