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	$177.96	10.360%	$196.3967	$196.40	$196.40	$196.40
Purchase #2	$48.88	13.634%	$55.5443	$55.54	$55.55	$55.50
Purchase #3	$170.56	3.328%	$176.2362	$176.24	$176.25	$176.20
Purchase #4	$174.91	12.146%	$196.1546	$196.15	$196.15	$196.20
Purchase #5	$127.38	10.614%	$140.9001	$140.90	$140.90	$140.90
Purchase #6	$157.66	4.866%	$165.3317	$165.33	$165.35	$165.30
Purchase #7	$77.45	12.557%	$87.1754	$87.18	$87.20	$87.20
7 purchase totals =	$934.80		$1,017.7390	$1,017.74	$1,017.80	$1,017.70