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	$192.66	11.534%	$214.8814	$214.88	$214.90	$214.90
Purchase #2	$104.58	4.543%	$109.3311	$109.33	$109.35	$109.30
Purchase #3	$188.53	4.345%	$196.7216	$196.72	$196.70	$196.70
Purchase #4	$241.53	4.236%	$251.7612	$251.76	$251.75	$251.80
Purchase #5	$170.72	12.839%	$192.6387	$192.64	$192.65	$192.60
Purchase #6	$118.88	11.695%	$132.783	$132.78	$132.80	$132.80
Purchase #7	$84.65	10.402%	$93.4553	$93.46	$93.45	$93.50
7 purchase totals =	$1,101.55		$1,191.5723	$1,191.57	$1,191.60	$1,191.60