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	$109.59	5.256%	$115.3501	$115.35	$115.35	$115.40
Purchase #2	$67.75	8.258%	$73.3448	$73.34	$73.35	$73.30
Purchase #3	$57.27	3.861%	$59.4812	$59.48	$59.50	$59.50
Purchase #4	$84.82	5.211%	$89.24	$89.24	$89.25	$89.20
Purchase #5	$232.54	11.235%	$258.6659	$258.67	$258.65	$258.70
Purchase #6	$240.95	11.130%	$267.7677	$267.77	$267.75	$267.80
Purchase #7	$151.42	6.714%	$161.5863	$161.59	$161.60	$161.60
7 purchase totals =	$944.34		$1,025.4360	$1,025.44	$1,025.45	$1,025.50