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	$223.44	6.319%	$237.5592	$237.56	$237.55	$237.60
Purchase #2	$49.50	7.511%	$53.2179	$53.22	$53.20	$53.20
Purchase #3	$82.83	9.359%	$90.5821	$90.58	$90.60	$90.60
Purchase #4	$95.43	10.165%	$105.1305	$105.13	$105.15	$105.10
Purchase #5	$202.45	9.675%	$222.037	$222.04	$222.05	$222.00
Purchase #6	$147.36	13.770%	$167.6515	$167.65	$167.65	$167.70
Purchase #7	$159.44	7.630%	$171.6053	$171.61	$171.60	$171.60
7 purchase totals =	$960.45		$1,047.7835	$1,047.79	$1,047.80	$1,047.80