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	$53.42	11.862%	$59.7567	$59.76	$59.75	$59.80
Purchase #2	$152.52	13.337%	$172.8616	$172.86	$172.85	$172.90
Purchase #3	$245.50	6.699%	$261.946	$261.95	$261.95	$261.90
Purchase #4	$74.68	3.641%	$77.3991	$77.40	$77.40	$77.40
Purchase #5	$160.57	6.838%	$171.5498	$171.55	$171.55	$171.50
Purchase #6	$159.66	12.453%	$179.5425	$179.54	$179.55	$179.50
Purchase #7	$90.57	12.575%	$101.9592	$101.96	$101.95	$102.00
7 purchase totals =	$936.92		$1,025.0149	$1,025.02	$1,025.00	$1,025.00