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	$222.61	5.481%	$234.8113	$234.81	$234.80	$234.80
Purchase #2	$169.66	5.636%	$179.222	$179.22	$179.20	$179.20
Purchase #3	$161.64	6.629%	$172.3551	$172.36	$172.35	$172.40
Purchase #4	$6.29	3.205%	$6.4916	$6.49	$6.50	$6.50
Purchase #5	$68.46	5.668%	$72.3403	$72.34	$72.35	$72.30
Purchase #6	$84.56	13.312%	$95.8166	$95.82	$95.80	$95.80
Purchase #7	$221.31	9.382%	$242.0733	$242.07	$242.05	$242.10
7 purchase totals =	$934.53		$1,003.1102	$1,003.11	$1,003.05	$1,003.10