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	$222.97	5.409%	$235.0304	$235.03	$235.05	$235.00
Purchase #2	$160.56	12.394%	$180.4598	$180.46	$180.45	$180.50
Purchase #3	$54.87	6.655%	$58.5216	$58.52	$58.50	$58.50
Purchase #4	$203.85	3.461%	$210.9052	$210.91	$210.90	$210.90
Purchase #5	$44.98	12.179%	$50.4581	$50.46	$50.45	$50.50
Purchase #6	$40.52	6.651%	$43.215	$43.22	$43.20	$43.20
Purchase #7	$209.33	11.661%	$233.74	$233.74	$233.75	$233.70
7 purchase totals =	$937.08		$1,012.3301	$1,012.34	$1,012.30	$1,012.30