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	$61.36	6.208%	$65.1692	$65.17	$65.15	$65.20
Purchase #2	$198.76	3.495%	$205.7067	$205.71	$205.70	$205.70
Purchase #3	$9.51	12.447%	$10.6937	$10.69	$10.70	$10.70
Purchase #4	$245.28	5.663%	$259.1702	$259.17	$259.15	$259.20
Purchase #5	$181.41	8.425%	$196.6938	$196.69	$196.70	$196.70
Purchase #6	$72.75	12.559%	$81.8867	$81.89	$81.90	$81.90
Purchase #7	$209.69	3.466%	$216.9579	$216.96	$216.95	$217.00
7 purchase totals =	$978.76		$1,036.2782	$1,036.28	$1,036.25	$1,036.40