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	$116.48	9.417%	$127.4489	$127.45	$127.45	$127.40
Purchase #2	$116.64	6.125%	$123.7842	$123.78	$123.80	$123.80
Purchase #3	$143.57	6.174%	$152.434	$152.43	$152.45	$152.40
Purchase #4	$7.27	4.603%	$7.6046	$7.60	$7.60	$7.60
Purchase #5	$118.46	12.480%	$133.2438	$133.24	$133.25	$133.20
Purchase #6	$74.57	3.609%	$77.2612	$77.26	$77.25	$77.30
Purchase #7	$215.64	7.189%	$231.1424	$231.14	$231.15	$231.10
7 purchase totals =	$792.63		$852.9191	$852.90	$852.95	$852.80