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	$153.43	9.545%	$168.0749	$168.07	$168.05	$168.10
Purchase #2	$223.48	12.540%	$251.5044	$251.50	$251.50	$251.50
Purchase #3	$33.67	5.562%	$35.5427	$35.54	$35.55	$35.50
Purchase #4	$69.55	11.220%	$77.3535	$77.35	$77.35	$77.40
Purchase #5	$77.56	9.765%	$85.1337	$85.13	$85.15	$85.10
Purchase #6	$216.93	6.848%	$231.7854	$231.79	$231.80	$231.80
Purchase #7	$166.27	5.626%	$175.6244	$175.62	$175.60	$175.60
7 purchase totals =	$940.89		$1,025.0190	$1,025.00	$1,025.00	$1,025.00