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	$216.75	10.121%	$238.6873	$238.69	$238.70	$238.70
Purchase #2	$189.31	3.785%	$196.4754	$196.48	$196.50	$196.50
Purchase #3	$104.62	9.601%	$114.6646	$114.66	$114.65	$114.70
Purchase #4	$35.45	10.651%	$39.2258	$39.23	$39.25	$39.20
Purchase #5	$92.44	3.245%	$95.4397	$95.44	$95.45	$95.40
Purchase #6	$170.79	9.865%	$187.6384	$187.64	$187.65	$187.60
Purchase #7	$187.52	13.670%	$213.154	$213.15	$213.15	$213.20
7 purchase totals =	$996.88		$1,085.2852	$1,085.29	$1,085.35	$1,085.30