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	$215.29	10.582%	$238.072	$238.07	$238.05	$238.10
Purchase #2	$75.79	12.205%	$85.0402	$85.04	$85.05	$85.00
Purchase #3	$99.27	9.713%	$108.9121	$108.91	$108.90	$108.90
Purchase #4	$227.57	9.818%	$249.9128	$249.91	$249.90	$249.90
Purchase #5	$86.25	3.112%	$88.9341	$88.93	$88.95	$88.90
Purchase #6	$216.77	3.179%	$223.6611	$223.66	$223.65	$223.70
Purchase #7	$116.25	4.848%	$121.8858	$121.89	$121.90	$121.90
7 purchase totals =	$1,037.19		$1,116.4181	$1,116.41	$1,116.40	$1,116.40