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	$106.36	10.411%	$117.4331	$117.43	$117.45	$117.40
Purchase #2	$100.71	4.236%	$104.9761	$104.98	$105.00	$105.00
Purchase #3	$186.73	3.468%	$193.2058	$193.21	$193.20	$193.20
Purchase #4	$59.94	6.792%	$64.0111	$64.01	$64.00	$64.00
Purchase #5	$80.53	11.243%	$89.584	$89.58	$89.60	$89.60
Purchase #6	$20.56	4.864%	$21.56	$21.56	$21.55	$21.60
Purchase #7	$184.88	6.372%	$196.6606	$196.66	$196.65	$196.70
7 purchase totals =	$739.71		$787.4307	$787.43	$787.45	$787.50