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	$195.92	9.751%	$215.0242	$215.02	$215.00	$215.00
Purchase #2	$53.45	7.432%	$57.4224	$57.42	$57.40	$57.40
Purchase #3	$102.95	6.480%	$109.6212	$109.62	$109.60	$109.60
Purchase #4	$164.67	6.577%	$175.5003	$175.50	$175.50	$175.50
Purchase #5	$87.78	8.604%	$95.3326	$95.33	$95.35	$95.30
Purchase #6	$168.56	7.764%	$181.647	$181.65	$181.65	$181.60
Purchase #7	$123.59	6.268%	$131.3366	$131.34	$131.35	$131.30
7 purchase totals =	$896.92		$965.8843	$965.88	$965.85	$965.70