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	$85.70	10.646%	$94.8236	$94.82	$94.80	$94.80
Purchase #2	$248.96	13.379%	$282.2684	$282.27	$282.25	$282.30
Purchase #3	$213.46	7.651%	$229.7918	$229.79	$229.80	$229.80
Purchase #4	$8.59	3.498%	$8.8905	$8.89	$8.90	$8.90
Purchase #5	$50.84	4.525%	$53.1405	$53.14	$53.15	$53.10
Purchase #6	$233.72	7.207%	$250.5642	$250.56	$250.55	$250.60
Purchase #7	$108.59	4.445%	$113.4168	$113.42	$113.40	$113.40
7 purchase totals =	$949.86		$1,032.8958	$1,032.89	$1,032.85	$1,032.90