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	$185.42	8.585%	$201.3383	$201.34	$201.35	$201.30
Purchase #2	$62.98	7.228%	$67.5322	$67.53	$67.55	$67.50
Purchase #3	$32.30	12.675%	$36.394	$36.39	$36.40	$36.40
Purchase #4	$99.38	13.715%	$113.01	$113.01	$113.00	$113.00
Purchase #5	$32.47	3.294%	$33.5396	$33.54	$33.55	$33.50
Purchase #6	$200.50	10.666%	$221.8853	$221.89	$221.90	$221.90
Purchase #7	$53.37	13.695%	$60.679	$60.68	$60.70	$60.70
7 purchase totals =	$666.42		$734.3784	$734.38	$734.45	$734.30