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	$183.33	9.352%	$200.475	$200.48	$200.50	$200.50
Purchase #2	$33.40	3.751%	$34.6528	$34.65	$34.65	$34.70
Purchase #3	$225.98	10.632%	$250.0062	$250.01	$250.00	$250.00
Purchase #4	$92.31	13.787%	$105.0368	$105.04	$105.05	$105.00
Purchase #5	$22.86	10.630%	$25.29	$25.29	$25.30	$25.30
Purchase #6	$230.33	5.671%	$243.392	$243.39	$243.40	$243.40
Purchase #7	$218.33	8.844%	$237.6391	$237.64	$237.65	$237.60
7 purchase totals =	$1,006.54		$1,096.4919	$1,096.50	$1,096.55	$1,096.50