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	$187.31	4.832%	$196.3608	$196.36	$196.35	$196.40
Purchase #2	$248.76	4.692%	$260.4318	$260.43	$260.45	$260.40
Purchase #3	$214.37	12.498%	$241.162	$241.16	$241.15	$241.20
Purchase #4	$249.41	11.272%	$277.5235	$277.52	$277.50	$277.50
Purchase #5	$157.42	11.455%	$175.4525	$175.45	$175.45	$175.50
Purchase #6	$119.35	6.395%	$126.9824	$126.98	$127.00	$127.00
Purchase #7	$78.35	6.366%	$83.3378	$83.34	$83.35	$83.30
7 purchase totals =	$1,254.97		$1,361.2508	$1,361.24	$1,361.25	$1,361.30