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	$131.26	7.404%	$140.9785	$140.98	$141.00	$141.00
Purchase #2	$35.43	13.309%	$40.1454	$40.15	$40.15	$40.10
Purchase #3	$214.31	11.230%	$238.377	$238.38	$238.40	$238.40
Purchase #4	$198.74	10.330%	$219.2698	$219.27	$219.25	$219.30
Purchase #5	$178.58	4.304%	$186.2661	$186.27	$186.25	$186.30
Purchase #6	$183.65	13.323%	$208.1177	$208.12	$208.10	$208.10
Purchase #7	$58.65	6.209%	$62.2916	$62.29	$62.30	$62.30
7 purchase totals =	$1,000.62		$1,095.4461	$1,095.46	$1,095.45	$1,095.50