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	$198.56	5.849%	$210.1738	$210.17	$210.15	$210.20
Purchase #2	$176.49	5.258%	$185.7698	$185.77	$185.75	$185.80
Purchase #3	$213.65	3.523%	$221.1769	$221.18	$221.20	$221.20
Purchase #4	$52.59	6.292%	$55.899	$55.90	$55.90	$55.90
Purchase #5	$167.85	10.741%	$185.8788	$185.88	$185.90	$185.90
Purchase #6	$198.72	5.195%	$209.0435	$209.04	$209.05	$209.00
Purchase #7	$69.66	12.523%	$78.3835	$78.38	$78.40	$78.40
7 purchase totals =	$1,077.52		$1,146.3253	$1,146.32	$1,146.35	$1,146.40