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	$190.75	7.603%	$205.2527	$205.25	$205.25	$205.30
Purchase #2	$107.57	4.703%	$112.629	$112.63	$112.65	$112.60
Purchase #3	$35.59	3.163%	$36.7157	$36.72	$36.70	$36.70
Purchase #4	$196.98	9.346%	$215.3898	$215.39	$215.40	$215.40
Purchase #5	$238.59	9.739%	$261.8263	$261.83	$261.85	$261.80
Purchase #6	$108.27	7.358%	$116.2365	$116.24	$116.25	$116.20
Purchase #7	$118.92	3.474%	$123.0513	$123.05	$123.05	$123.10
7 purchase totals =	$996.67		$1,071.1013	$1,071.11	$1,071.15	$1,071.10