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	$166.97	4.670%	$174.7675	$174.77	$174.75	$174.80
Purchase #2	$245.25	10.353%	$270.6407	$270.64	$270.65	$270.60
Purchase #3	$194.54	7.637%	$209.397	$209.40	$209.40	$209.40
Purchase #4	$68.56	4.332%	$71.53	$71.53	$71.55	$71.50
Purchase #5	$112.75	9.170%	$123.0892	$123.09	$123.10	$123.10
Purchase #6	$56.69	9.541%	$62.0988	$62.10	$62.10	$62.10
Purchase #7	$162.93	5.545%	$171.9645	$171.96	$171.95	$172.00
7 purchase totals =	$1,007.69		$1,083.4877	$1,083.49	$1,083.50	$1,083.50