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	$184.80	8.403%	$200.3287	$200.33	$200.35	$200.30
Purchase #2	$45.28	4.789%	$47.4485	$47.45	$47.45	$47.40
Purchase #3	$94.51	3.538%	$97.8538	$97.85	$97.85	$97.90
Purchase #4	$247.50	13.776%	$281.5956	$281.60	$281.60	$281.60
Purchase #5	$222.92	12.212%	$250.143	$250.14	$250.15	$250.10
Purchase #6	$134.99	6.285%	$143.4741	$143.47	$143.45	$143.50
Purchase #7	$39.56	7.614%	$42.5721	$42.57	$42.55	$42.60
7 purchase totals =	$969.56		$1,063.4158	$1,063.41	$1,063.40	$1,063.40