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	$211.43	3.756%	$219.3713	$219.37	$219.35	$219.40
Purchase #2	$209.66	8.566%	$227.6195	$227.62	$227.60	$227.60
Purchase #3	$33.40	5.178%	$35.1295	$35.13	$35.15	$35.10
Purchase #4	$136.73	5.475%	$144.216	$144.22	$144.20	$144.20
Purchase #5	$159.28	4.788%	$166.9063	$166.91	$166.90	$166.90
Purchase #6	$202.29	13.470%	$229.5385	$229.54	$229.55	$229.50
Purchase #7	$180.43	4.654%	$188.8272	$188.83	$188.85	$188.80
7 purchase totals =	$1,133.22		$1,211.6083	$1,211.62	$1,211.60	$1,211.50