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	$100.63	10.340%	$111.0351	$111.04	$111.05	$111.00
Purchase #2	$31.96	3.442%	$33.0601	$33.06	$33.05	$33.10
Purchase #3	$187.89	5.860%	$198.9004	$198.90	$198.90	$198.90
Purchase #4	$162.26	3.619%	$168.1322	$168.13	$168.15	$168.10
Purchase #5	$116.56	6.523%	$124.1632	$124.16	$124.15	$124.20
Purchase #6	$172.33	13.744%	$196.015	$196.02	$196.00	$196.00
Purchase #7	$229.35	6.648%	$244.5972	$244.60	$244.60	$244.60
7 purchase totals =	$1,000.98		$1,075.9032	$1,075.91	$1,075.90	$1,075.90