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	$146.37	4.149%	$152.4429	$152.44	$152.45	$152.40
Purchase #2	$177.57	4.573%	$185.6903	$185.69	$185.70	$185.70
Purchase #3	$195.91	10.530%	$216.5393	$216.54	$216.55	$216.50
Purchase #4	$70.55	11.781%	$78.8615	$78.86	$78.85	$78.90
Purchase #5	$33.40	4.170%	$34.7928	$34.79	$34.80	$34.80
Purchase #6	$167.71	11.710%	$187.3488	$187.35	$187.35	$187.30
Purchase #7	$172.42	12.242%	$193.5277	$193.53	$193.55	$193.50
7 purchase totals =	$963.93		$1,049.2033	$1,049.20	$1,049.25	$1,049.10