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	$115.29	10.506%	$127.4024	$127.40	$127.40	$127.40
Purchase #2	$175.43	6.603%	$187.0136	$187.01	$187.00	$187.00
Purchase #3	$51.26	12.844%	$57.8438	$57.84	$57.85	$57.80
Purchase #4	$242.78	13.501%	$275.5577	$275.56	$275.55	$275.60
Purchase #5	$249.29	10.465%	$275.3782	$275.38	$275.40	$275.40
Purchase #6	$43.89	10.756%	$48.6108	$48.61	$48.60	$48.60
Purchase #7	$115.97	7.751%	$124.9588	$124.96	$124.95	$125.00
7 purchase totals =	$993.91		$1,096.7653	$1,096.76	$1,096.75	$1,096.80