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	$156.46	12.446%	$175.933	$175.93	$175.95	$175.90
Purchase #2	$61.87	8.714%	$67.2614	$67.26	$67.25	$67.30
Purchase #3	$220.88	5.280%	$232.5425	$232.54	$232.55	$232.50
Purchase #4	$14.58	5.224%	$15.3417	$15.34	$15.35	$15.30
Purchase #5	$136.51	10.142%	$150.3548	$150.35	$150.35	$150.40
Purchase #6	$158.46	6.591%	$168.9041	$168.90	$168.90	$168.90
Purchase #7	$194.41	8.672%	$211.2692	$211.27	$211.25	$211.30
7 purchase totals =	$943.17		$1,021.6067	$1,021.59	$1,021.60	$1,021.60