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	$200.98	5.140%	$211.3104	$211.31	$211.30	$211.30
Purchase #2	$62.81	12.447%	$70.628	$70.63	$70.65	$70.60
Purchase #3	$223.55	11.600%	$249.4818	$249.48	$249.50	$249.50
Purchase #4	$227.32	7.274%	$243.8553	$243.86	$243.85	$243.90
Purchase #5	$30.58	13.115%	$34.5906	$34.59	$34.60	$34.60
Purchase #6	$18.86	10.817%	$20.9001	$20.90	$20.90	$20.90
Purchase #7	$218.57	11.583%	$243.887	$243.89	$243.90	$243.90
7 purchase totals =	$982.67		$1,074.6532	$1,074.66	$1,074.70	$1,074.70