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	$173.42	13.443%	$196.7329	$196.73	$196.75	$196.70
Purchase #2	$128.56	4.601%	$134.475	$134.48	$134.50	$134.50
Purchase #3	$11.39	10.154%	$12.5465	$12.55	$12.55	$12.50
Purchase #4	$199.97	9.257%	$218.4812	$218.48	$218.50	$218.50
Purchase #5	$176.28	13.131%	$199.4273	$199.43	$199.45	$199.40
Purchase #6	$225.41	11.150%	$250.5432	$250.54	$250.55	$250.50
Purchase #7	$202.86	8.298%	$219.6933	$219.69	$219.70	$219.70
7 purchase totals =	$1,117.89		$1,231.8994	$1,231.90	$1,232.00	$1,231.80