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	$176.55	12.812%	$199.1696	$199.17	$199.15	$199.20
Purchase #2	$124.67	4.351%	$130.0944	$130.09	$130.10	$130.10
Purchase #3	$62.40	3.541%	$64.6096	$64.61	$64.60	$64.60
Purchase #4	$57.57	7.273%	$61.7571	$61.76	$61.75	$61.80
Purchase #5	$123.27	3.750%	$127.8926	$127.89	$127.90	$127.90
Purchase #6	$179.64	4.682%	$188.0507	$188.05	$188.05	$188.10
Purchase #7	$234.35	3.637%	$242.8733	$242.87	$242.85	$242.90
7 purchase totals =	$958.45		$1,014.4473	$1,014.44	$1,014.40	$1,014.60