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	$184.43	8.140%	$199.4426	$199.44	$199.45	$199.40
Purchase #2	$45.99	13.291%	$52.1025	$52.10	$52.10	$52.10
Purchase #3	$177.87	4.178%	$185.3014	$185.30	$185.30	$185.30
Purchase #4	$133.64	12.626%	$150.5134	$150.51	$150.50	$150.50
Purchase #5	$229.56	7.312%	$246.3454	$246.35	$246.35	$246.30
Purchase #6	$188.76	11.502%	$210.4712	$210.47	$210.45	$210.50
Purchase #7	$99.83	3.545%	$103.369	$103.37	$103.35	$103.40
7 purchase totals =	$1,060.08		$1,147.5455	$1,147.54	$1,147.50	$1,147.50