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	$196.52	13.122%	$222.3074	$222.31	$222.30	$222.30
Purchase #2	$17.68	11.648%	$19.7394	$19.74	$19.75	$19.70
Purchase #3	$92.83	13.849%	$105.686	$105.69	$105.70	$105.70
Purchase #4	$172.57	13.834%	$196.4433	$196.44	$196.45	$196.40
Purchase #5	$24.25	10.789%	$26.8663	$26.87	$26.85	$26.90
Purchase #6	$5.31	4.566%	$5.5525	$5.55	$5.55	$5.60
Purchase #7	$244.31	10.809%	$270.7175	$270.72	$270.70	$270.70
7 purchase totals =	$753.47		$847.3124	$847.32	$847.30	$847.30