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	$76.32	9.398%	$83.4926	$83.49	$83.50	$83.50
Purchase #2	$181.25	7.573%	$194.9761	$194.98	$195.00	$195.00
Purchase #3	$164.54	7.507%	$176.892	$176.89	$176.90	$176.90
Purchase #4	$64.55	10.771%	$71.5027	$71.50	$71.50	$71.50
Purchase #5	$244.73	4.305%	$255.2656	$255.27	$255.25	$255.30
Purchase #6	$148.77	4.731%	$155.8083	$155.81	$155.80	$155.80
Purchase #7	$175.41	6.401%	$186.638	$186.64	$186.65	$186.60
7 purchase totals =	$1,055.57		$1,124.5753	$1,124.58	$1,124.60	$1,124.60