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	$78.56	10.675%	$86.9463	$86.95	$86.95	$86.90
Purchase #2	$246.72	6.169%	$261.9402	$261.94	$261.95	$261.90
Purchase #3	$94.81	12.726%	$106.8755	$106.88	$106.90	$106.90
Purchase #4	$218.57	8.194%	$236.4796	$236.48	$236.50	$236.50
Purchase #5	$90.32	13.406%	$102.4283	$102.43	$102.45	$102.40
Purchase #6	$247.49	9.644%	$271.3579	$271.36	$271.35	$271.40
Purchase #7	$72.28	8.778%	$78.6247	$78.62	$78.60	$78.60
7 purchase totals =	$1,048.75		$1,144.6525	$1,144.66	$1,144.70	$1,144.60