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	$182.33	7.601%	$196.1889	$196.19	$196.20	$196.20
Purchase #2	$223.34	13.461%	$253.4038	$253.40	$253.40	$253.40
Purchase #3	$7.35	6.434%	$7.8229	$7.82	$7.80	$7.80
Purchase #4	$219.99	12.644%	$247.8055	$247.81	$247.80	$247.80
Purchase #5	$238.65	10.545%	$263.8156	$263.82	$263.80	$263.80
Purchase #6	$134.66	11.455%	$150.0853	$150.09	$150.10	$150.10
Purchase #7	$42.92	4.607%	$44.8973	$44.90	$44.90	$44.90
7 purchase totals =	$1,049.24		$1,164.0193	$1,164.03	$1,164.00	$1,164.00