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	$175.92	5.212%	$185.089	$185.09	$185.10	$185.10
Purchase #2	$55.32	13.113%	$62.5741	$62.57	$62.55	$62.60
Purchase #3	$104.68	3.520%	$108.3647	$108.36	$108.35	$108.40
Purchase #4	$213.84	7.772%	$230.4596	$230.46	$230.45	$230.50
Purchase #5	$167.90	10.271%	$185.145	$185.15	$185.15	$185.10
Purchase #6	$63.59	13.533%	$72.1956	$72.20	$72.20	$72.20
Purchase #7	$229.73	12.343%	$258.0856	$258.09	$258.10	$258.10
7 purchase totals =	$1,010.98		$1,101.9136	$1,101.92	$1,101.90	$1,102.00