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	$120.26	9.489%	$131.6715	$131.67	$131.65	$131.70
Purchase #2	$102.31	9.306%	$111.831	$111.83	$111.85	$111.80
Purchase #3	$23.32	9.474%	$25.5293	$25.53	$25.55	$25.50
Purchase #4	$160.97	11.486%	$179.459	$179.46	$179.45	$179.50
Purchase #5	$76.96	10.744%	$85.2286	$85.23	$85.25	$85.20
Purchase #6	$247.40	10.173%	$272.568	$272.57	$272.55	$272.60
Purchase #7	$229.68	12.642%	$258.7161	$258.72	$258.70	$258.70
7 purchase totals =	$960.90		$1,065.0035	$1,065.01	$1,065.00	$1,065.00