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	$198.61	8.676%	$215.8414	$215.84	$215.85	$215.80
Purchase #2	$85.68	3.295%	$88.5032	$88.50	$88.50	$88.50
Purchase #3	$32.73	3.799%	$33.9734	$33.97	$33.95	$34.00
Purchase #4	$165.51	10.224%	$182.4317	$182.43	$182.45	$182.40
Purchase #5	$233.56	3.102%	$240.805	$240.81	$240.80	$240.80
Purchase #6	$75.48	3.866%	$78.3981	$78.40	$78.40	$78.40
Purchase #7	$210.70	11.242%	$234.3869	$234.39	$234.40	$234.40
7 purchase totals =	$1,002.27		$1,074.3397	$1,074.34	$1,074.35	$1,074.30