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	$103.37	5.765%	$109.3293	$109.33	$109.35	$109.30
Purchase #2	$13.77	5.428%	$14.5174	$14.52	$14.50	$14.50
Purchase #3	$141.25	8.162%	$152.7788	$152.78	$152.80	$152.80
Purchase #4	$143.80	8.658%	$156.2502	$156.25	$156.25	$156.30
Purchase #5	$186.82	13.190%	$211.4616	$211.46	$211.45	$211.50
Purchase #6	$181.49	7.108%	$194.3903	$194.39	$194.40	$194.40
Purchase #7	$164.70	10.834%	$182.5436	$182.54	$182.55	$182.50
7 purchase totals =	$935.20		$1,021.2712	$1,021.27	$1,021.30	$1,021.30