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	$87.38	11.129%	$97.1045	$97.10	$97.10	$97.10
Purchase #2	$66.89	7.260%	$71.7462	$71.75	$71.75	$71.70
Purchase #3	$138.96	4.253%	$144.87	$144.87	$144.85	$144.90
Purchase #4	$199.81	5.281%	$210.362	$210.36	$210.35	$210.40
Purchase #5	$123.71	5.709%	$130.7726	$130.77	$130.75	$130.80
Purchase #6	$221.33	5.655%	$233.8462	$233.85	$233.85	$233.80
Purchase #7	$218.76	10.803%	$242.3926	$242.39	$242.40	$242.40
7 purchase totals =	$1,056.84		$1,131.0941	$1,131.09	$1,131.05	$1,131.10