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	$189.84	3.724%	$196.9096	$196.91	$196.90	$196.90
Purchase #2	$160.83	7.237%	$172.4693	$172.47	$172.45	$172.50
Purchase #3	$196.66	4.451%	$205.4133	$205.41	$205.40	$205.40
Purchase #4	$248.59	9.174%	$271.3956	$271.40	$271.40	$271.40
Purchase #5	$240.68	9.704%	$264.0356	$264.04	$264.05	$264.00
Purchase #6	$93.76	9.284%	$102.4647	$102.46	$102.45	$102.50
Purchase #7	$142.39	4.126%	$148.265	$148.27	$148.25	$148.30
7 purchase totals =	$1,272.75		$1,360.9531	$1,360.96	$1,360.90	$1,361.00