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	$44.38	7.872%	$47.8736	$47.87	$47.85	$47.90
Purchase #2	$158.90	8.204%	$171.9362	$171.94	$171.95	$171.90
Purchase #3	$167.34	8.786%	$182.0425	$182.04	$182.05	$182.00
Purchase #4	$248.46	5.289%	$261.601	$261.60	$261.60	$261.60
Purchase #5	$115.83	10.289%	$127.7477	$127.75	$127.75	$127.70
Purchase #6	$152.73	4.121%	$159.024	$159.02	$159.00	$159.00
Purchase #7	$138.40	5.848%	$146.4936	$146.49	$146.50	$146.50
7 purchase totals =	$1,026.04		$1,096.7186	$1,096.71	$1,096.70	$1,096.60