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	$55.54	7.598%	$59.7599	$59.76	$59.75	$59.80
Purchase #2	$229.75	5.209%	$241.7177	$241.72	$241.70	$241.70
Purchase #3	$161.38	13.343%	$182.9129	$182.91	$182.90	$182.90
Purchase #4	$48.35	13.427%	$54.842	$54.84	$54.85	$54.80
Purchase #5	$93.48	11.268%	$104.0133	$104.01	$104.00	$104.00
Purchase #6	$218.33	13.118%	$246.9705	$246.97	$246.95	$247.00
Purchase #7	$151.59	13.606%	$172.2153	$172.22	$172.20	$172.20
7 purchase totals =	$958.42		$1,062.4316	$1,062.43	$1,062.35	$1,062.40