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	$193.60	8.333%	$209.7327	$209.73	$209.75	$209.70
Purchase #2	$23.55	9.813%	$25.861	$25.86	$25.85	$25.90
Purchase #3	$80.84	3.383%	$83.5748	$83.57	$83.55	$83.60
Purchase #4	$226.88	3.252%	$234.2581	$234.26	$234.25	$234.30
Purchase #5	$30.73	3.456%	$31.792	$31.79	$31.80	$31.80
Purchase #6	$65.76	9.578%	$72.0585	$72.06	$72.05	$72.10
Purchase #7	$187.77	4.530%	$196.276	$196.28	$196.30	$196.30
7 purchase totals =	$809.13		$853.5531	$853.55	$853.55	$853.70