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	$185.70	5.822%	$196.5115	$196.51	$196.50	$196.50
Purchase #2	$151.77	6.691%	$161.9249	$161.92	$161.90	$161.90
Purchase #3	$64.43	4.599%	$67.3931	$67.39	$67.40	$67.40
Purchase #4	$5.30	4.628%	$5.5453	$5.55	$5.55	$5.50
Purchase #5	$168.32	3.522%	$174.2482	$174.25	$174.25	$174.20
Purchase #6	$243.37	11.674%	$271.781	$271.78	$271.80	$271.80
Purchase #7	$173.47	10.358%	$191.438	$191.44	$191.45	$191.40
7 purchase totals =	$992.36		$1,068.8420	$1,068.84	$1,068.85	$1,068.70