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	$82.37	5.540%	$86.9333	$86.93	$86.95	$86.90
Purchase #2	$80.68	3.650%	$83.6248	$83.62	$83.60	$83.60
Purchase #3	$134.36	10.703%	$148.7406	$148.74	$148.75	$148.70
Purchase #4	$239.46	10.866%	$265.4797	$265.48	$265.50	$265.50
Purchase #5	$126.35	13.506%	$143.4148	$143.41	$143.40	$143.40
Purchase #6	$250.91	5.447%	$264.5771	$264.58	$264.60	$264.60
Purchase #7	$94.51	8.751%	$102.7806	$102.78	$102.80	$102.80
7 purchase totals =	$1,008.64		$1,095.5509	$1,095.54	$1,095.60	$1,095.50