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	$71.28	10.333%	$78.6454	$78.65	$78.65	$78.60
Purchase #2	$10.77	9.344%	$11.7763	$11.78	$11.80	$11.80
Purchase #3	$100.28	6.114%	$106.4111	$106.41	$106.40	$106.40
Purchase #4	$157.44	9.851%	$172.9494	$172.95	$172.95	$172.90
Purchase #5	$189.79	8.666%	$206.2372	$206.24	$206.25	$206.20
Purchase #6	$76.91	7.597%	$82.7529	$82.75	$82.75	$82.80
Purchase #7	$150.91	10.665%	$167.0046	$167.00	$167.00	$167.00
7 purchase totals =	$757.38		$825.7769	$825.78	$825.80	$825.70