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	$191.84	9.427%	$209.9248	$209.92	$209.90	$209.90
Purchase #2	$242.36	10.754%	$268.4234	$268.42	$268.40	$268.40
Purchase #3	$68.49	5.140%	$72.0104	$72.01	$72.00	$72.00
Purchase #4	$160.82	6.839%	$171.8185	$171.82	$171.80	$171.80
Purchase #5	$76.47	12.299%	$85.875	$85.88	$85.90	$85.90
Purchase #6	$125.86	8.680%	$136.7846	$136.78	$136.80	$136.80
Purchase #7	$69.78	6.327%	$74.195	$74.20	$74.20	$74.20
7 purchase totals =	$935.62		$1,019.0317	$1,019.03	$1,019.00	$1,019.00