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	$216.28	7.734%	$233.0071	$233.01	$233.00	$233.00
Purchase #2	$186.69	11.435%	$208.038	$208.04	$208.05	$208.00
Purchase #3	$63.30	13.379%	$71.7689	$71.77	$71.75	$71.80
Purchase #4	$108.58	3.411%	$112.2837	$112.28	$112.30	$112.30
Purchase #5	$79.29	12.564%	$89.252	$89.25	$89.25	$89.30
Purchase #6	$70.73	12.127%	$79.3074	$79.31	$79.30	$79.30
Purchase #7	$236.45	5.380%	$249.171	$249.17	$249.15	$249.20
7 purchase totals =	$961.32		$1,042.8281	$1,042.83	$1,042.80	$1,042.90