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	$214.81	7.742%	$231.4406	$231.44	$231.45	$231.40
Purchase #2	$5.49	11.473%	$6.1199	$6.12	$6.10	$6.10
Purchase #3	$235.29	4.684%	$246.311	$246.31	$246.30	$246.30
Purchase #4	$248.31	8.270%	$268.8452	$268.85	$268.85	$268.80
Purchase #5	$130.30	6.687%	$139.0132	$139.01	$139.00	$139.00
Purchase #6	$40.71	4.436%	$42.5159	$42.52	$42.50	$42.50
Purchase #7	$141.33	3.697%	$146.555	$146.56	$146.55	$146.60
7 purchase totals =	$1,016.24		$1,080.8008	$1,080.81	$1,080.75	$1,080.70