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	$173.29	13.276%	$196.296	$196.30	$196.30	$196.30
Purchase #2	$75.58	4.272%	$78.8088	$78.81	$78.80	$78.80
Purchase #3	$206.82	10.851%	$229.262	$229.26	$229.25	$229.30
Purchase #4	$180.57	5.814%	$191.0683	$191.07	$191.05	$191.10
Purchase #5	$131.50	3.388%	$135.9552	$135.96	$135.95	$136.00
Purchase #6	$111.93	10.415%	$123.5875	$123.59	$123.60	$123.60
Purchase #7	$63.83	12.526%	$71.8253	$71.83	$71.85	$71.80
7 purchase totals =	$943.52		$1,026.8031	$1,026.82	$1,026.80	$1,026.90