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	$142.83	7.452%	$153.4737	$153.47	$153.45	$153.50
Purchase #2	$128.32	8.565%	$139.3106	$139.31	$139.30	$139.30
Purchase #3	$155.55	8.555%	$168.8573	$168.86	$168.85	$168.90
Purchase #4	$168.93	10.783%	$187.1457	$187.15	$187.15	$187.10
Purchase #5	$92.92	12.514%	$104.548	$104.55	$104.55	$104.50
Purchase #6	$179.91	3.310%	$185.865	$185.87	$185.85	$185.90
Purchase #7	$63.89	11.695%	$71.3619	$71.36	$71.35	$71.40
7 purchase totals =	$932.35		$1,010.5622	$1,010.57	$1,010.50	$1,010.60