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	$179.30	7.484%	$192.7188	$192.72	$192.70	$192.70
Purchase #2	$70.39	11.494%	$78.4806	$78.48	$78.50	$78.50
Purchase #3	$217.79	3.363%	$225.1143	$225.11	$225.10	$225.10
Purchase #4	$194.71	5.207%	$204.8485	$204.85	$204.85	$204.80
Purchase #5	$84.25	12.830%	$95.0593	$95.06	$95.05	$95.10
Purchase #6	$168.75	6.569%	$179.8352	$179.84	$179.85	$179.80
Purchase #7	$223.62	6.634%	$238.455	$238.46	$238.45	$238.50
7 purchase totals =	$1,138.81		$1,214.5117	$1,214.52	$1,214.50	$1,214.50