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	$60.54	12.221%	$67.9386	$67.94	$67.95	$67.90
Purchase #2	$10.78	7.727%	$11.613	$11.61	$11.60	$11.60
Purchase #3	$211.41	7.488%	$227.2404	$227.24	$227.25	$227.20
Purchase #4	$97.62	10.299%	$107.6739	$107.67	$107.65	$107.70
Purchase #5	$95.55	3.261%	$98.6659	$98.67	$98.65	$98.70
Purchase #6	$80.90	5.285%	$85.1756	$85.18	$85.20	$85.20
Purchase #7	$112.98	12.696%	$127.3239	$127.32	$127.30	$127.30
7 purchase totals =	$669.78		$725.6313	$725.63	$725.60	$725.60