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	$196.26	13.272%	$222.3076	$222.31	$222.30	$222.30
Purchase #2	$201.95	6.298%	$214.6688	$214.67	$214.65	$214.70
Purchase #3	$14.83	11.167%	$16.4861	$16.49	$16.50	$16.50
Purchase #4	$219.28	9.661%	$240.4646	$240.46	$240.45	$240.50
Purchase #5	$99.90	11.601%	$111.4894	$111.49	$111.50	$111.50
Purchase #6	$38.33	7.752%	$41.3013	$41.30	$41.30	$41.30
Purchase #7	$15.41	7.154%	$16.5124	$16.51	$16.50	$16.50
7 purchase totals =	$785.96		$863.2302	$863.23	$863.20	$863.30