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	$49.43	13.852%	$56.277	$56.28	$56.30	$56.30
Purchase #2	$95.31	3.314%	$98.4686	$98.47	$98.45	$98.50
Purchase #3	$195.35	6.588%	$208.2197	$208.22	$208.20	$208.20
Purchase #4	$166.84	5.167%	$175.4606	$175.46	$175.45	$175.50
Purchase #5	$181.92	8.263%	$196.952	$196.95	$196.95	$197.00
Purchase #6	$152.67	7.595%	$164.2653	$164.27	$164.25	$164.30
Purchase #7	$203.91	4.648%	$213.3877	$213.39	$213.40	$213.40
7 purchase totals =	$1,045.43		$1,113.0309	$1,113.04	$1,113.00	$1,113.20