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	$148.35	12.551%	$166.9694	$166.97	$166.95	$167.00
Purchase #2	$104.73	4.660%	$109.6104	$109.61	$109.60	$109.60
Purchase #3	$85.49	6.748%	$91.2589	$91.26	$91.25	$91.30
Purchase #4	$182.39	3.543%	$188.8521	$188.85	$188.85	$188.90
Purchase #5	$140.37	3.760%	$145.6479	$145.65	$145.65	$145.60
Purchase #6	$50.95	8.715%	$55.3903	$55.39	$55.40	$55.40
Purchase #7	$244.59	3.818%	$253.9284	$253.93	$253.95	$253.90
7 purchase totals =	$956.87		$1,011.6574	$1,011.66	$1,011.65	$1,011.70