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	$187.47	11.745%	$209.4884	$209.49	$209.50	$209.50
Purchase #2	$80.50	11.380%	$89.6609	$89.66	$89.65	$89.70
Purchase #3	$89.96	8.321%	$97.4456	$97.45	$97.45	$97.40
Purchase #4	$138.91	5.413%	$146.4292	$146.43	$146.45	$146.40
Purchase #5	$228.74	7.207%	$245.2253	$245.23	$245.25	$245.20
Purchase #6	$144.26	5.405%	$152.0573	$152.06	$152.05	$152.10
Purchase #7	$171.45	11.363%	$190.9319	$190.93	$190.95	$190.90
7 purchase totals =	$1,041.29		$1,131.2386	$1,131.25	$1,131.30	$1,131.20