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	$95.80	7.690%	$103.167	$103.17	$103.15	$103.20
Purchase #2	$208.38	7.112%	$223.2	$223.20	$223.20	$223.20
Purchase #3	$141.65	4.200%	$147.5993	$147.60	$147.60	$147.60
Purchase #4	$150.43	11.228%	$167.3203	$167.32	$167.30	$167.30
Purchase #5	$33.80	7.185%	$36.2285	$36.23	$36.25	$36.20
Purchase #6	$148.76	11.734%	$166.2155	$166.22	$166.20	$166.20
Purchase #7	$190.35	7.145%	$203.9505	$203.95	$203.95	$204.00
7 purchase totals =	$969.17		$1,047.6811	$1,047.69	$1,047.65	$1,047.70