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	$190.82	3.216%	$196.9568	$196.96	$196.95	$197.00
Purchase #2	$37.71	6.188%	$40.0435	$40.04	$40.05	$40.00
Purchase #3	$185.75	6.844%	$198.4627	$198.46	$198.45	$198.50
Purchase #4	$231.67	11.510%	$258.3352	$258.34	$258.35	$258.30
Purchase #5	$89.94	7.319%	$96.5227	$96.52	$96.50	$96.50
Purchase #6	$41.84	11.671%	$46.7231	$46.72	$46.70	$46.70
Purchase #7	$179.90	11.392%	$200.3942	$200.39	$200.40	$200.40
7 purchase totals =	$957.63		$1,037.4382	$1,037.43	$1,037.40	$1,037.40