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	$230.39	13.779%	$262.1354	$262.14	$262.15	$262.10
Purchase #2	$58.31	5.179%	$61.3299	$61.33	$61.35	$61.30
Purchase #3	$127.76	9.347%	$139.7017	$139.70	$139.70	$139.70
Purchase #4	$170.67	12.347%	$191.7426	$191.74	$191.75	$191.70
Purchase #5	$156.82	5.557%	$165.5345	$165.53	$165.55	$165.50
Purchase #6	$175.64	13.829%	$199.9293	$199.93	$199.95	$199.90
Purchase #7	$128.77	10.555%	$142.3617	$142.36	$142.35	$142.40
7 purchase totals =	$1,048.36		$1,162.7351	$1,162.73	$1,162.80	$1,162.60