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	$112.48	11.178%	$125.053	$125.05	$125.05	$125.10
Purchase #2	$214.94	13.774%	$244.5458	$244.55	$244.55	$244.50
Purchase #3	$51.52	3.128%	$53.1315	$53.13	$53.15	$53.10
Purchase #4	$53.63	5.276%	$56.4595	$56.46	$56.45	$56.50
Purchase #5	$84.42	5.682%	$89.2167	$89.22	$89.20	$89.20
Purchase #6	$235.66	8.734%	$256.2425	$256.24	$256.25	$256.20
Purchase #7	$135.74	12.637%	$152.8935	$152.89	$152.90	$152.90
7 purchase totals =	$888.39		$977.5425	$977.54	$977.55	$977.50