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	$190.38	6.611%	$202.966	$202.97	$202.95	$203.00
Purchase #2	$250.52	4.773%	$262.4773	$262.48	$262.50	$262.50
Purchase #3	$173.84	3.277%	$179.5367	$179.54	$179.55	$179.50
Purchase #4	$118.27	4.407%	$123.4822	$123.48	$123.50	$123.50
Purchase #5	$180.65	8.844%	$196.6267	$196.63	$196.65	$196.60
Purchase #6	$98.94	5.690%	$104.5697	$104.57	$104.55	$104.60
Purchase #7	$156.88	9.488%	$171.7648	$171.76	$171.75	$171.80
7 purchase totals =	$1,169.48		$1,241.4234	$1,241.43	$1,241.45	$1,241.50