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	$209.56	4.630%	$219.2626	$219.26	$219.25	$219.30
Purchase #2	$216.55	11.474%	$241.3969	$241.40	$241.40	$241.40
Purchase #3	$141.50	4.862%	$148.3797	$148.38	$148.40	$148.40
Purchase #4	$116.74	12.312%	$131.113	$131.11	$131.10	$131.10
Purchase #5	$81.70	5.175%	$85.928	$85.93	$85.95	$85.90
Purchase #6	$203.43	6.720%	$217.1005	$217.10	$217.10	$217.10
Purchase #7	$221.95	7.617%	$238.8559	$238.86	$238.85	$238.90
7 purchase totals =	$1,191.43		$1,282.0366	$1,282.04	$1,282.05	$1,282.10