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	$195.66	9.556%	$214.3573	$214.36	$214.35	$214.40
Purchase #2	$226.55	10.742%	$250.886	$250.89	$250.90	$250.90
Purchase #3	$130.68	9.541%	$143.1482	$143.15	$143.15	$143.10
Purchase #4	$41.58	8.744%	$45.2158	$45.22	$45.20	$45.20
Purchase #5	$173.36	9.522%	$189.8673	$189.87	$189.85	$189.90
Purchase #6	$192.89	13.494%	$218.9186	$218.92	$218.90	$218.90
Purchase #7	$43.88	4.678%	$45.9327	$45.93	$45.95	$45.90
7 purchase totals =	$1,004.60		$1,108.3259	$1,108.34	$1,108.30	$1,108.30