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	$178.60	9.774%	$196.0564	$196.06	$196.05	$196.10
Purchase #2	$166.27	9.420%	$181.9326	$181.93	$181.95	$181.90
Purchase #3	$250.72	5.578%	$264.7052	$264.71	$264.70	$264.70
Purchase #4	$242.66	12.630%	$273.308	$273.31	$273.30	$273.30
Purchase #5	$52.25	11.287%	$58.1475	$58.15	$58.15	$58.10
Purchase #6	$44.61	9.273%	$48.7467	$48.75	$48.75	$48.70
Purchase #7	$17.72	6.633%	$18.8954	$18.90	$18.90	$18.90
7 purchase totals =	$952.83		$1,041.7918	$1,041.81	$1,041.80	$1,041.70