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	$147.85	7.435%	$158.8426	$158.84	$158.85	$158.80
Purchase #2	$133.91	13.662%	$152.2048	$152.20	$152.20	$152.20
Purchase #3	$83.89	12.742%	$94.5793	$94.58	$94.60	$94.60
Purchase #4	$244.82	3.730%	$253.9518	$253.95	$253.95	$254.00
Purchase #5	$210.96	7.752%	$227.3136	$227.31	$227.30	$227.30
Purchase #6	$159.73	4.820%	$167.429	$167.43	$167.45	$167.40
Purchase #7	$84.55	13.429%	$95.9042	$95.90	$95.90	$95.90
7 purchase totals =	$1,065.71		$1,150.2253	$1,150.21	$1,150.25	$1,150.20