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	$75.73	10.747%	$83.8687	$83.87	$83.85	$83.90
Purchase #2	$192.89	6.859%	$206.1203	$206.12	$206.10	$206.10
Purchase #3	$126.40	12.608%	$142.3365	$142.34	$142.35	$142.30
Purchase #4	$200.30	8.249%	$216.8227	$216.82	$216.80	$216.80
Purchase #5	$176.72	8.594%	$191.9073	$191.91	$191.90	$191.90
Purchase #6	$160.55	5.205%	$168.9066	$168.91	$168.90	$168.90
Purchase #7	$13.36	12.552%	$15.0369	$15.04	$15.05	$15.00
7 purchase totals =	$945.95		$1,024.9990	$1,025.01	$1,024.95	$1,024.90