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	$183.54	5.704%	$194.0091	$194.01	$194.00	$194.00
Purchase #2	$244.57	7.517%	$262.9543	$262.95	$262.95	$263.00
Purchase #3	$225.46	13.561%	$256.0346	$256.03	$256.05	$256.00
Purchase #4	$250.44	9.453%	$274.1141	$274.11	$274.10	$274.10
Purchase #5	$37.64	7.742%	$40.5541	$40.55	$40.55	$40.60
Purchase #6	$21.50	3.309%	$22.2114	$22.21	$22.20	$22.20
Purchase #7	$53.54	4.443%	$55.9188	$55.92	$55.90	$55.90
7 purchase totals =	$1,016.69		$1,105.7964	$1,105.78	$1,105.75	$1,105.80