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	$248.32	7.718%	$267.4853	$267.49	$267.50	$267.50
Purchase #2	$185.81	13.862%	$211.567	$211.57	$211.55	$211.60
Purchase #3	$71.84	3.574%	$74.4076	$74.41	$74.40	$74.40
Purchase #4	$115.29	11.294%	$128.3109	$128.31	$128.30	$128.30
Purchase #5	$28.68	10.818%	$31.7826	$31.78	$31.80	$31.80
Purchase #6	$221.68	8.201%	$239.86	$239.86	$239.85	$239.90
Purchase #7	$56.31	11.148%	$62.5874	$62.59	$62.60	$62.60
7 purchase totals =	$927.93		$1,016.0008	$1,016.01	$1,016.00	$1,016.10