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	$79.63	3.679%	$82.5596	$82.56	$82.55	$82.60
Purchase #2	$200.85	6.568%	$214.0418	$214.04	$214.05	$214.00
Purchase #3	$224.88	8.271%	$243.4798	$243.48	$243.50	$243.50
Purchase #4	$243.40	3.324%	$251.4906	$251.49	$251.50	$251.50
Purchase #5	$8.73	6.510%	$9.2983	$9.30	$9.30	$9.30
Purchase #6	$102.57	6.352%	$109.0852	$109.09	$109.10	$109.10
Purchase #7	$103.46	6.103%	$109.7742	$109.77	$109.75	$109.80
7 purchase totals =	$963.52		$1,019.7295	$1,019.73	$1,019.75	$1,019.80