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	$80.54	5.471%	$84.9463	$84.95	$84.95	$84.90
Purchase #2	$156.85	13.787%	$178.4749	$178.47	$178.45	$178.50
Purchase #3	$36.77	10.385%	$40.5886	$40.59	$40.60	$40.60
Purchase #4	$244.69	6.213%	$259.8926	$259.89	$259.90	$259.90
Purchase #5	$173.81	8.544%	$188.6603	$188.66	$188.65	$188.70
Purchase #6	$220.97	9.423%	$241.792	$241.79	$241.80	$241.80
Purchase #7	$61.56	9.518%	$67.4193	$67.42	$67.40	$67.40
7 purchase totals =	$975.19		$1,061.7740	$1,061.77	$1,061.75	$1,061.80