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	$176.52	12.473%	$198.5373	$198.54	$198.55	$198.50
Purchase #2	$143.46	3.463%	$148.428	$148.43	$148.45	$148.40
Purchase #3	$104.89	4.178%	$109.2723	$109.27	$109.25	$109.30
Purchase #4	$36.48	7.696%	$39.2875	$39.29	$39.30	$39.30
Purchase #5	$219.88	7.861%	$237.1648	$237.16	$237.15	$237.20
Purchase #6	$91.70	3.615%	$95.015	$95.02	$95.00	$95.00
Purchase #7	$200.39	11.560%	$223.5551	$223.56	$223.55	$223.60
7 purchase totals =	$973.32		$1,051.2600	$1,051.27	$1,051.25	$1,051.30