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	$186.57	11.246%	$207.5517	$207.55	$207.55	$207.60
Purchase #2	$130.65	10.619%	$144.5237	$144.52	$144.50	$144.50
Purchase #3	$59.98	7.243%	$64.3244	$64.32	$64.30	$64.30
Purchase #4	$28.55	10.506%	$31.5495	$31.55	$31.55	$31.50
Purchase #5	$115.45	10.686%	$127.787	$127.79	$127.80	$127.80
Purchase #6	$143.47	3.110%	$147.9319	$147.93	$147.95	$147.90
Purchase #7	$204.29	12.412%	$229.6465	$229.65	$229.65	$229.60
7 purchase totals =	$868.96		$953.3147	$953.31	$953.30	$953.20