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	$125.31	11.275%	$139.4387	$139.44	$139.45	$139.40
Purchase #2	$12.46	5.529%	$13.1489	$13.15	$13.15	$13.10
Purchase #3	$154.96	4.354%	$161.707	$161.71	$161.70	$161.70
Purchase #4	$246.56	10.740%	$273.0405	$273.04	$273.05	$273.00
Purchase #5	$166.57	10.321%	$183.7617	$183.76	$183.75	$183.80
Purchase #6	$109.78	4.240%	$114.4347	$114.43	$114.45	$114.40
Purchase #7	$180.93	10.733%	$200.3492	$200.35	$200.35	$200.30
7 purchase totals =	$996.57		$1,085.8807	$1,085.88	$1,085.90	$1,085.70