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	$209.59	8.365%	$227.1222	$227.12	$227.10	$227.10
Purchase #2	$191.76	7.717%	$206.5581	$206.56	$206.55	$206.60
Purchase #3	$218.64	4.766%	$229.0604	$229.06	$229.05	$229.10
Purchase #4	$139.80	5.279%	$147.18	$147.18	$147.20	$147.20
Purchase #5	$85.40	8.389%	$92.5642	$92.56	$92.55	$92.60
Purchase #6	$112.75	9.862%	$123.8694	$123.87	$123.85	$123.90
Purchase #7	$48.75	6.359%	$51.85	$51.85	$51.85	$51.90
7 purchase totals =	$1,006.69		$1,078.2043	$1,078.20	$1,078.15	$1,078.40