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	$207.56	7.106%	$222.3092	$222.31	$222.30	$222.30
Purchase #2	$204.92	8.193%	$221.7091	$221.71	$221.70	$221.70
Purchase #3	$168.57	9.441%	$184.4847	$184.48	$184.50	$184.50
Purchase #4	$114.68	9.525%	$125.6033	$125.60	$125.60	$125.60
Purchase #5	$223.95	11.641%	$250.02	$250.02	$250.00	$250.00
Purchase #6	$10.52	7.790%	$11.3395	$11.34	$11.35	$11.30
Purchase #7	$84.65	6.782%	$90.391	$90.39	$90.40	$90.40
7 purchase totals =	$1,014.85		$1,105.8568	$1,105.85	$1,105.85	$1,105.80