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	$68.37	4.807%	$71.6565	$71.66	$71.65	$71.70
Purchase #2	$7.33	4.623%	$7.6689	$7.67	$7.65	$7.70
Purchase #3	$83.25	9.312%	$91.0022	$91.00	$91.00	$91.00
Purchase #4	$186.44	7.334%	$200.1135	$200.11	$200.10	$200.10
Purchase #5	$222.88	8.462%	$241.7401	$241.74	$241.75	$241.70
Purchase #6	$37.85	5.697%	$40.0063	$40.01	$40.00	$40.00
Purchase #7	$99.66	3.850%	$103.4969	$103.50	$103.50	$103.50
7 purchase totals =	$705.78		$755.6844	$755.69	$755.65	$755.70