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	$196.32	3.461%	$203.1146	$203.11	$203.10	$203.10
Purchase #2	$170.60	13.731%	$194.0251	$194.03	$194.05	$194.00
Purchase #3	$76.80	4.651%	$80.372	$80.37	$80.35	$80.40
Purchase #4	$171.37	11.745%	$191.4974	$191.50	$191.50	$191.50
Purchase #5	$30.36	4.196%	$31.6339	$31.63	$31.65	$31.60
Purchase #6	$234.33	10.784%	$259.6001	$259.60	$259.60	$259.60
Purchase #7	$148.46	12.726%	$167.353	$167.35	$167.35	$167.40
7 purchase totals =	$1,028.24		$1,127.5961	$1,127.59	$1,127.60	$1,127.60