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	$201.80	7.536%	$217.0076	$217.01	$217.00	$217.00
Purchase #2	$198.91	7.568%	$213.9635	$213.96	$213.95	$214.00
Purchase #3	$190.84	12.838%	$215.34	$215.34	$215.35	$215.30
Purchase #4	$81.53	10.269%	$89.9023	$89.90	$89.90	$89.90
Purchase #5	$102.56	10.230%	$113.0519	$113.05	$113.05	$113.10
Purchase #6	$183.82	11.107%	$204.2369	$204.24	$204.25	$204.20
Purchase #7	$72.73	7.821%	$78.4182	$78.42	$78.40	$78.40
7 purchase totals =	$1,032.19		$1,131.9204	$1,131.92	$1,131.90	$1,131.90