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	$113.33	4.760%	$118.7245	$118.72	$118.70	$118.70
Purchase #2	$19.55	11.225%	$21.7445	$21.74	$21.75	$21.70
Purchase #3	$57.35	7.327%	$61.552	$61.55	$61.55	$61.60
Purchase #4	$170.34	8.765%	$185.2703	$185.27	$185.25	$185.30
Purchase #5	$134.45	10.628%	$148.7393	$148.74	$148.75	$148.70
Purchase #6	$131.27	4.332%	$136.9566	$136.96	$136.95	$137.00
Purchase #7	$186.77	12.151%	$209.4644	$209.46	$209.45	$209.50
7 purchase totals =	$813.06		$882.4516	$882.44	$882.40	$882.50