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	$169.66	7.468%	$182.3302	$182.33	$182.35	$182.30
Purchase #2	$107.86	5.337%	$113.6165	$113.62	$113.60	$113.60
Purchase #3	$29.81	5.154%	$31.3464	$31.35	$31.35	$31.30
Purchase #4	$166.33	13.245%	$188.3604	$188.36	$188.35	$188.40
Purchase #5	$242.33	8.440%	$262.7827	$262.78	$262.80	$262.80
Purchase #6	$94.46	10.695%	$104.5625	$104.56	$104.55	$104.60
Purchase #7	$125.50	13.866%	$142.9018	$142.90	$142.90	$142.90
7 purchase totals =	$935.95		$1,025.9005	$1,025.90	$1,025.90	$1,025.90