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	$211.43	10.369%	$233.3532	$233.35	$233.35	$233.40
Purchase #2	$177.30	10.561%	$196.0247	$196.02	$196.00	$196.00
Purchase #3	$56.52	10.681%	$62.5569	$62.56	$62.55	$62.60
Purchase #4	$116.86	8.870%	$127.2255	$127.23	$127.25	$127.20
Purchase #5	$185.62	9.316%	$202.9124	$202.91	$202.90	$202.90
Purchase #6	$51.79	5.744%	$54.7648	$54.76	$54.75	$54.80
Purchase #7	$54.34	11.483%	$60.5799	$60.58	$60.60	$60.60
7 purchase totals =	$853.86		$937.4174	$937.41	$937.40	$937.50