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	$172.40	13.697%	$196.0136	$196.01	$196.00	$196.00
Purchase #2	$139.33	8.716%	$151.474	$151.47	$151.45	$151.50
Purchase #3	$31.39	12.330%	$35.2604	$35.26	$35.25	$35.30
Purchase #4	$189.51	10.591%	$209.581	$209.58	$209.60	$209.60
Purchase #5	$208.79	10.411%	$230.5271	$230.53	$230.55	$230.50
Purchase #6	$108.43	11.716%	$121.1337	$121.13	$121.15	$121.10
Purchase #7	$141.48	6.220%	$150.2801	$150.28	$150.30	$150.30
7 purchase totals =	$991.33		$1,094.2699	$1,094.26	$1,094.30	$1,094.30