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	$141.88	8.497%	$153.9355	$153.94	$153.95	$153.90
Purchase #2	$95.47	10.815%	$105.7951	$105.80	$105.80	$105.80
Purchase #3	$83.92	11.332%	$93.4298	$93.43	$93.45	$93.40
Purchase #4	$180.73	9.624%	$198.1235	$198.12	$198.10	$198.10
Purchase #5	$175.84	11.590%	$196.2199	$196.22	$196.20	$196.20
Purchase #6	$16.64	9.626%	$18.2418	$18.24	$18.25	$18.20
Purchase #7	$228.40	11.107%	$253.7684	$253.77	$253.75	$253.80
7 purchase totals =	$922.88		$1,019.5140	$1,019.52	$1,019.50	$1,019.40