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	$194.42	7.645%	$209.2834	$209.28	$209.30	$209.30
Purchase #2	$184.72	11.233%	$205.4696	$205.47	$205.45	$205.50
Purchase #3	$31.42	6.569%	$33.484	$33.48	$33.50	$33.50
Purchase #4	$82.38	12.386%	$92.5836	$92.58	$92.60	$92.60
Purchase #5	$83.74	8.519%	$90.8738	$90.87	$90.85	$90.90
Purchase #6	$175.89	13.343%	$199.359	$199.36	$199.35	$199.40
Purchase #7	$177.68	11.713%	$198.4917	$198.49	$198.50	$198.50
7 purchase totals =	$930.25		$1,029.5451	$1,029.53	$1,029.55	$1,029.70