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	$67.94	13.526%	$77.1296	$77.13	$77.15	$77.10
Purchase #2	$215.85	3.233%	$222.8284	$222.83	$222.85	$222.80
Purchase #3	$52.53	8.616%	$57.056	$57.06	$57.05	$57.10
Purchase #4	$10.80	12.874%	$12.1904	$12.19	$12.20	$12.20
Purchase #5	$244.85	10.793%	$271.2767	$271.28	$271.30	$271.30
Purchase #6	$245.95	9.694%	$269.7924	$269.79	$269.80	$269.80
Purchase #7	$113.89	9.375%	$124.5672	$124.57	$124.55	$124.60
7 purchase totals =	$951.81		$1,034.8407	$1,034.85	$1,034.90	$1,034.90