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	$190.85	12.367%	$214.4524	$214.45	$214.45	$214.50
Purchase #2	$10.34	12.456%	$11.628	$11.63	$11.65	$11.60
Purchase #3	$13.52	13.486%	$15.3433	$15.34	$15.35	$15.30
Purchase #4	$64.61	6.112%	$68.559	$68.56	$68.55	$68.60
Purchase #5	$168.91	12.547%	$190.1031	$190.10	$190.10	$190.10
Purchase #6	$102.93	8.736%	$111.922	$111.92	$111.90	$111.90
Purchase #7	$82.27	13.161%	$93.0976	$93.10	$93.10	$93.10
7 purchase totals =	$633.43		$705.1054	$705.10	$705.10	$705.10