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	$185.75	12.857%	$209.6319	$209.63	$209.65	$209.60
Purchase #2	$213.90	4.611%	$223.7629	$223.76	$223.75	$223.80
Purchase #3	$62.48	7.560%	$67.2035	$67.20	$67.20	$67.20
Purchase #4	$221.40	12.634%	$249.3717	$249.37	$249.35	$249.40
Purchase #5	$55.82	12.362%	$62.7205	$62.72	$62.70	$62.70
Purchase #6	$17.43	12.462%	$19.6021	$19.60	$19.60	$19.60
Purchase #7	$169.50	5.777%	$179.292	$179.29	$179.30	$179.30
7 purchase totals =	$926.28		$1,011.5846	$1,011.57	$1,011.55	$1,011.60