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	$195.46	6.712%	$208.5793	$208.58	$208.60	$208.60
Purchase #2	$147.64	3.213%	$152.3837	$152.38	$152.40	$152.40
Purchase #3	$86.59	8.741%	$94.1588	$94.16	$94.15	$94.20
Purchase #4	$92.96	12.628%	$104.699	$104.70	$104.70	$104.70
Purchase #5	$63.62	5.530%	$67.1382	$67.14	$67.15	$67.10
Purchase #6	$78.80	5.233%	$82.9236	$82.92	$82.90	$82.90
Purchase #7	$232.71	4.268%	$242.6421	$242.64	$242.65	$242.60
7 purchase totals =	$897.78		$952.5247	$952.52	$952.55	$952.50