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	$188.91	3.836%	$196.1566	$196.16	$196.15	$196.20
Purchase #2	$137.47	5.570%	$145.1271	$145.13	$145.15	$145.10
Purchase #3	$41.89	4.130%	$43.6201	$43.62	$43.60	$43.60
Purchase #4	$106.97	4.865%	$112.1741	$112.17	$112.15	$112.20
Purchase #5	$219.55	11.479%	$244.7521	$244.75	$244.75	$244.80
Purchase #6	$245.51	11.190%	$272.9826	$272.98	$273.00	$273.00
Purchase #7	$188.28	5.603%	$198.8293	$198.83	$198.85	$198.80
7 purchase totals =	$1,128.58		$1,213.6419	$1,213.64	$1,213.65	$1,213.70