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	$102.63	11.333%	$114.2611	$114.26	$114.25	$114.30
Purchase #2	$188.56	5.573%	$199.0684	$199.07	$199.05	$199.10
Purchase #3	$215.92	11.360%	$240.4485	$240.45	$240.45	$240.40
Purchase #4	$72.50	13.693%	$82.4274	$82.43	$82.45	$82.40
Purchase #5	$240.33	6.502%	$255.9563	$255.96	$255.95	$256.00
Purchase #6	$6.36	9.246%	$6.948	$6.95	$6.95	$6.90
Purchase #7	$244.29	7.862%	$263.4961	$263.50	$263.50	$263.50
7 purchase totals =	$1,070.59		$1,162.6058	$1,162.62	$1,162.60	$1,162.60