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	$44.36	9.654%	$48.6425	$48.64	$48.65	$48.60
Purchase #2	$169.35	5.781%	$179.1401	$179.14	$179.15	$179.10
Purchase #3	$40.83	11.399%	$45.4842	$45.48	$45.50	$45.50
Purchase #4	$86.72	10.676%	$95.9782	$95.98	$96.00	$96.00
Purchase #5	$164.41	13.663%	$186.8733	$186.87	$186.85	$186.90
Purchase #6	$239.45	3.442%	$247.6919	$247.69	$247.70	$247.70
Purchase #7	$236.82	9.749%	$259.9076	$259.91	$259.90	$259.90
7 purchase totals =	$981.94		$1,063.7178	$1,063.71	$1,063.75	$1,063.70