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	$208.88	4.857%	$219.0253	$219.03	$219.05	$219.00
Purchase #2	$212.29	4.367%	$221.5607	$221.56	$221.55	$221.60
Purchase #3	$198.32	9.324%	$216.8114	$216.81	$216.80	$216.80
Purchase #4	$114.34	11.534%	$127.528	$127.53	$127.55	$127.50
Purchase #5	$164.34	4.450%	$171.6531	$171.65	$171.65	$171.70
Purchase #6	$102.57	8.593%	$111.3838	$111.38	$111.40	$111.40
Purchase #7	$14.62	6.109%	$15.5131	$15.51	$15.50	$15.50
7 purchase totals =	$1,015.36		$1,083.4754	$1,083.47	$1,083.50	$1,083.50