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	$183.67	4.190%	$191.3658	$191.37	$191.35	$191.40
Purchase #2	$213.63	4.186%	$222.5726	$222.57	$222.55	$222.60
Purchase #3	$21.72	11.726%	$24.2669	$24.27	$24.25	$24.30
Purchase #4	$228.93	11.145%	$254.4442	$254.44	$254.45	$254.40
Purchase #5	$178.74	4.382%	$186.5724	$186.57	$186.55	$186.60
Purchase #6	$150.88	5.310%	$158.8917	$158.89	$158.90	$158.90
Purchase #7	$156.83	6.227%	$166.5958	$166.60	$166.60	$166.60
7 purchase totals =	$1,134.40		$1,204.7094	$1,204.71	$1,204.65	$1,204.80