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	$131.59	7.707%	$141.7316	$141.73	$141.75	$141.70
Purchase #2	$195.67	6.790%	$208.956	$208.96	$208.95	$209.00
Purchase #3	$108.26	11.770%	$121.0022	$121.00	$121.00	$121.00
Purchase #4	$98.65	13.169%	$111.6412	$111.64	$111.65	$111.60
Purchase #5	$141.78	7.436%	$152.3228	$152.32	$152.30	$152.30
Purchase #6	$102.56	13.519%	$116.4251	$116.43	$116.45	$116.40
Purchase #7	$145.59	7.521%	$156.5398	$156.54	$156.55	$156.50
7 purchase totals =	$924.10		$1,008.6187	$1,008.62	$1,008.65	$1,008.50