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	$180.82	11.131%	$200.9471	$200.95	$200.95	$200.90
Purchase #2	$245.60	10.195%	$270.6389	$270.64	$270.65	$270.60
Purchase #3	$51.55	3.820%	$53.5192	$53.52	$53.50	$53.50
Purchase #4	$79.52	12.672%	$89.5968	$89.60	$89.60	$89.60
Purchase #5	$78.65	7.132%	$84.2593	$84.26	$84.25	$84.30
Purchase #6	$157.71	12.570%	$177.5341	$177.53	$177.55	$177.50
Purchase #7	$175.27	6.853%	$187.2813	$187.28	$187.30	$187.30
7 purchase totals =	$969.12		$1,063.7767	$1,063.78	$1,063.80	$1,063.70