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	$205.54	5.580%	$217.0091	$217.01	$217.00	$217.00
Purchase #2	$70.57	5.836%	$74.6885	$74.69	$74.70	$74.70
Purchase #3	$235.69	4.258%	$245.7257	$245.73	$245.75	$245.70
Purchase #4	$37.96	11.774%	$42.4294	$42.43	$42.45	$42.40
Purchase #5	$196.37	6.599%	$209.3285	$209.33	$209.35	$209.30
Purchase #6	$194.59	7.364%	$208.9196	$208.92	$208.90	$208.90
Purchase #7	$157.74	4.193%	$164.354	$164.35	$164.35	$164.40
7 purchase totals =	$1,098.46		$1,162.4548	$1,162.46	$1,162.50	$1,162.40