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	$185.90	12.750%	$209.6023	$209.60	$209.60	$209.60
Purchase #2	$64.29	12.722%	$72.469	$72.47	$72.45	$72.50
Purchase #3	$167.53	13.523%	$190.1851	$190.19	$190.20	$190.20
Purchase #4	$153.96	10.464%	$170.0704	$170.07	$170.05	$170.10
Purchase #5	$147.62	9.586%	$161.7709	$161.77	$161.75	$161.80
Purchase #6	$178.98	9.584%	$196.1334	$196.13	$196.15	$196.10
Purchase #7	$165.30	5.148%	$173.8096	$173.81	$173.80	$173.80
7 purchase totals =	$1,063.58		$1,174.0407	$1,174.04	$1,174.00	$1,174.10