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	$85.52	12.768%	$96.4392	$96.44	$96.45	$96.40
Purchase #2	$16.94	13.173%	$19.1715	$19.17	$19.15	$19.20
Purchase #3	$76.90	7.463%	$82.639	$82.64	$82.65	$82.60
Purchase #4	$180.37	5.281%	$189.8953	$189.90	$189.90	$189.90
Purchase #5	$84.32	6.590%	$89.8767	$89.88	$89.90	$89.90
Purchase #6	$240.29	9.554%	$263.2473	$263.25	$263.25	$263.20
Purchase #7	$42.35	7.467%	$45.5123	$45.51	$45.50	$45.50
7 purchase totals =	$726.69		$786.7813	$786.79	$786.80	$786.70