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	$82.58	7.239%	$88.558	$88.56	$88.55	$88.60
Purchase #2	$194.85	4.390%	$203.4039	$203.40	$203.40	$203.40
Purchase #3	$115.75	6.599%	$123.3883	$123.39	$123.40	$123.40
Purchase #4	$54.71	3.399%	$56.5696	$56.57	$56.55	$56.60
Purchase #5	$149.39	10.215%	$164.6502	$164.65	$164.65	$164.70
Purchase #6	$150.81	9.466%	$165.0857	$165.09	$165.10	$165.10
Purchase #7	$201.34	10.624%	$222.7304	$222.73	$222.75	$222.70
7 purchase totals =	$949.43		$1,024.3861	$1,024.39	$1,024.40	$1,024.50