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	$118.84	9.665%	$130.3259	$130.33	$130.35	$130.30
Purchase #2	$118.42	4.506%	$123.756	$123.76	$123.75	$123.80
Purchase #3	$118.98	11.759%	$132.9709	$132.97	$132.95	$133.00
Purchase #4	$123.39	4.732%	$129.2288	$129.23	$129.25	$129.20
Purchase #5	$131.62	10.352%	$145.2453	$145.25	$145.25	$145.20
Purchase #6	$206.39	9.250%	$225.4811	$225.48	$225.50	$225.50
Purchase #7	$117.37	11.801%	$131.2208	$131.22	$131.20	$131.20
7 purchase totals =	$935.01		$1,018.2288	$1,018.24	$1,018.25	$1,018.20