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	$68.64	3.459%	$71.0143	$71.01	$71.00	$71.00
Purchase #2	$74.56	4.107%	$77.6222	$77.62	$77.60	$77.60
Purchase #3	$170.54	4.427%	$178.0898	$178.09	$178.10	$178.10
Purchase #4	$147.90	9.699%	$162.2448	$162.24	$162.25	$162.20
Purchase #5	$137.49	7.781%	$148.1881	$148.19	$148.20	$148.20
Purchase #6	$175.86	11.483%	$196.054	$196.05	$196.05	$196.10
Purchase #7	$52.44	12.844%	$59.1754	$59.18	$59.20	$59.20
7 purchase totals =	$827.43		$892.3886	$892.38	$892.40	$892.40