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	$176.54	13.688%	$200.7048	$200.70	$200.70	$200.70
Purchase #2	$61.91	5.626%	$65.3931	$65.39	$65.40	$65.40
Purchase #3	$127.39	11.428%	$141.9481	$141.95	$141.95	$141.90
Purchase #4	$140.99	6.222%	$149.7624	$149.76	$149.75	$149.80
Purchase #5	$83.47	13.867%	$95.0448	$95.04	$95.05	$95.00
Purchase #6	$189.51	3.497%	$196.1372	$196.14	$196.15	$196.10
Purchase #7	$171.45	4.718%	$179.539	$179.54	$179.55	$179.50
7 purchase totals =	$951.26		$1,028.5294	$1,028.52	$1,028.55	$1,028.40