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	$194.39	4.740%	$203.6041	$203.60	$203.60	$203.60
Purchase #2	$70.71	3.869%	$73.4458	$73.45	$73.45	$73.40
Purchase #3	$131.35	12.756%	$148.105	$148.11	$148.10	$148.10
Purchase #4	$118.60	7.573%	$127.5816	$127.58	$127.60	$127.60
Purchase #5	$34.35	3.297%	$35.4825	$35.48	$35.50	$35.50
Purchase #6	$195.87	7.420%	$210.4036	$210.40	$210.40	$210.40
Purchase #7	$199.34	6.587%	$212.4705	$212.47	$212.45	$212.50
7 purchase totals =	$944.61		$1,011.0931	$1,011.09	$1,011.10	$1,011.10