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	$172.64	13.785%	$196.4384	$196.44	$196.45	$196.40
Purchase #2	$228.80	4.209%	$238.4302	$238.43	$238.45	$238.40
Purchase #3	$60.47	11.276%	$67.2886	$67.29	$67.30	$67.30
Purchase #4	$182.51	7.659%	$196.4884	$196.49	$196.50	$196.50
Purchase #5	$233.96	5.409%	$246.6149	$246.61	$246.60	$246.60
Purchase #6	$36.53	13.494%	$41.4594	$41.46	$41.45	$41.50
Purchase #7	$79.84	4.818%	$83.6867	$83.69	$83.70	$83.70
7 purchase totals =	$994.75		$1,070.4066	$1,070.41	$1,070.45	$1,070.40