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	$211.77	12.192%	$237.589	$237.59	$237.60	$237.60
Purchase #2	$201.56	7.427%	$216.5299	$216.53	$216.55	$216.50
Purchase #3	$189.50	10.182%	$208.7949	$208.79	$208.80	$208.80
Purchase #4	$46.40	6.214%	$49.2833	$49.28	$49.30	$49.30
Purchase #5	$90.41	11.673%	$100.9636	$100.96	$100.95	$101.00
Purchase #6	$102.36	9.143%	$111.7188	$111.72	$111.70	$111.70
Purchase #7	$114.82	6.657%	$122.4636	$122.46	$122.45	$122.50
7 purchase totals =	$956.82		$1,047.3431	$1,047.33	$1,047.35	$1,047.40