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	$144.71	5.222%	$152.2668	$152.27	$152.25	$152.30
Purchase #2	$208.92	13.774%	$237.6966	$237.70	$237.70	$237.70
Purchase #3	$191.94	8.815%	$208.8595	$208.86	$208.85	$208.90
Purchase #4	$55.33	12.807%	$62.4161	$62.42	$62.40	$62.40
Purchase #5	$126.83	11.367%	$141.2468	$141.25	$141.25	$141.20
Purchase #6	$168.60	9.873%	$185.2459	$185.25	$185.25	$185.20
Purchase #7	$114.70	13.162%	$129.7968	$129.80	$129.80	$129.80
7 purchase totals =	$1,011.03		$1,117.5285	$1,117.55	$1,117.50	$1,117.50