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	$171.27	8.805%	$186.3503	$186.35	$186.35	$186.40
Purchase #2	$23.81	4.689%	$24.9265	$24.93	$24.95	$24.90
Purchase #3	$74.69	5.743%	$78.9794	$78.98	$79.00	$79.00
Purchase #4	$178.50	12.269%	$200.4002	$200.40	$200.40	$200.40
Purchase #5	$132.34	11.335%	$147.3407	$147.34	$147.35	$147.30
Purchase #6	$169.43	10.641%	$187.459	$187.46	$187.45	$187.50
Purchase #7	$209.65	6.784%	$223.8727	$223.87	$223.85	$223.90
7 purchase totals =	$959.69		$1,049.3288	$1,049.33	$1,049.35	$1,049.40