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	$167.57	6.872%	$179.0854	$179.09	$179.10	$179.10
Purchase #2	$41.56	5.515%	$43.852	$43.85	$43.85	$43.90
Purchase #3	$225.94	4.418%	$235.922	$235.92	$235.90	$235.90
Purchase #4	$52.39	3.242%	$54.0885	$54.09	$54.10	$54.10
Purchase #5	$189.91	5.404%	$200.1727	$200.17	$200.15	$200.20
Purchase #6	$105.25	10.374%	$116.1686	$116.17	$116.15	$116.20
Purchase #7	$165.39	3.379%	$170.9785	$170.98	$171.00	$171.00
7 purchase totals =	$948.01		$1,000.2677	$1,000.27	$1,000.25	$1,000.40