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	$193.71	3.512%	$200.5131	$200.51	$200.50	$200.50
Purchase #2	$103.43	9.227%	$112.9735	$112.97	$112.95	$113.00
Purchase #3	$42.75	9.713%	$46.9023	$46.90	$46.90	$46.90
Purchase #4	$125.58	4.874%	$131.7008	$131.70	$131.70	$131.70
Purchase #5	$151.54	5.207%	$159.4307	$159.43	$159.45	$159.40
Purchase #6	$28.33	4.157%	$29.5077	$29.51	$29.50	$29.50
Purchase #7	$59.55	9.731%	$65.3448	$65.34	$65.35	$65.30
7 purchase totals =	$704.89		$746.3729	$746.36	$746.35	$746.30