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	$181.98	7.797%	$196.169	$196.17	$196.15	$196.20
Purchase #2	$86.41	5.871%	$91.4831	$91.48	$91.50	$91.50
Purchase #3	$14.38	9.321%	$15.7204	$15.72	$15.70	$15.70
Purchase #4	$224.57	11.121%	$249.5444	$249.54	$249.55	$249.50
Purchase #5	$125.28	9.636%	$137.352	$137.35	$137.35	$137.40
Purchase #6	$248.43	6.186%	$263.7979	$263.80	$263.80	$263.80
Purchase #7	$183.58	7.298%	$196.9777	$196.98	$197.00	$197.00
7 purchase totals =	$1,064.63		$1,151.0445	$1,151.04	$1,151.05	$1,151.10