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	$178.44	10.181%	$196.607	$196.61	$196.60	$196.60
Purchase #2	$83.96	5.545%	$88.6156	$88.62	$88.60	$88.60
Purchase #3	$81.54	8.150%	$88.1855	$88.19	$88.20	$88.20
Purchase #4	$246.80	4.738%	$258.4934	$258.49	$258.50	$258.50
Purchase #5	$47.63	12.472%	$53.5704	$53.57	$53.55	$53.60
Purchase #6	$128.66	13.227%	$145.6779	$145.68	$145.70	$145.70
Purchase #7	$169.51	4.801%	$177.6482	$177.65	$177.65	$177.60
7 purchase totals =	$936.54		$1,008.7980	$1,008.81	$1,008.80	$1,008.80