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	$132.81	11.775%	$148.4484	$148.45	$148.45	$148.40
Purchase #2	$112.27	3.231%	$115.8974	$115.90	$115.90	$115.90
Purchase #3	$33.52	5.272%	$35.2872	$35.29	$35.30	$35.30
Purchase #4	$79.59	6.872%	$85.0594	$85.06	$85.05	$85.10
Purchase #5	$241.69	5.771%	$255.6379	$255.64	$255.65	$255.60
Purchase #6	$122.40	7.457%	$131.5274	$131.53	$131.55	$131.50
Purchase #7	$180.29	6.253%	$191.5635	$191.56	$191.55	$191.60
7 purchase totals =	$902.57		$963.4212	$963.43	$963.45	$963.40