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	$193.41	3.623%	$200.4172	$200.42	$200.40	$200.40
Purchase #2	$24.64	10.803%	$27.3019	$27.30	$27.30	$27.30
Purchase #3	$127.97	6.829%	$136.7091	$136.71	$136.70	$136.70
Purchase #4	$151.31	13.737%	$172.0955	$172.10	$172.10	$172.10
Purchase #5	$89.42	4.555%	$93.4931	$93.49	$93.50	$93.50
Purchase #6	$179.42	10.609%	$198.4547	$198.45	$198.45	$198.50
Purchase #7	$190.66	9.282%	$208.3571	$208.36	$208.35	$208.40
7 purchase totals =	$956.83		$1,036.8286	$1,036.83	$1,036.80	$1,036.90