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	$173.33	13.386%	$196.532	$196.53	$196.55	$196.50
Purchase #2	$69.44	3.203%	$71.6642	$71.66	$71.65	$71.70
Purchase #3	$90.98	10.857%	$100.8577	$100.86	$100.85	$100.90
Purchase #4	$13.53	12.180%	$15.178	$15.18	$15.20	$15.20
Purchase #5	$214.38	3.368%	$221.6003	$221.60	$221.60	$221.60
Purchase #6	$145.72	9.214%	$159.1466	$159.15	$159.15	$159.10
Purchase #7	$124.77	13.435%	$141.5328	$141.53	$141.55	$141.50
7 purchase totals =	$832.15		$906.5116	$906.51	$906.55	$906.50